# Mathematical musings

2203 Views 18 Replies 7 Participants Last post by  BlueRam
You let us math types take a vacation and we start finding numbers to play with. My brain has latched on to this and I don't have sufficient knowledge to take the process to conclusion. If my thinking is invalid, someone can point out my errors and this can roll down the forum. If it has merit, then maybe it will start an interesting discussion. I'm going to obliquely reference both EI and PPS Pro--I'm neither attacking nor supporting either method. They were the starting points for my thinking and so that's where I'll start.

If I dose x amount of a nutrient weekly and change 50% of my water, then the math supports that the maximum level the nutrient will reach is 2x. (This is a convergent series and the formula is x/(1-r) where r is the percent of water remaining after a change. This must be the total amount of water in the system, including what's outside the tank in filters, sumps, etc.). The first question was if I change less than 50% can I predict the maximum level the nutrient will reach. The answer is yes. If I change 20%, then the maximum level will be 5x. If I only change 10% weekly, then the maximum level will be 10x. For simplicity in my thought process, and because I don't know the numbers, I'm going to ignore nutrient uptake by the plants (influenced by light, CO2 and plant mass and choices) and increased nutrients due to fish waste and excess food. Since land plants can be burned, stunted, and even killed by excess levels of nutrients, I would speculate the same can occur in aquatic plants. I've seen my own plants go from great growth to less great growth to a complete stop (at which point algae begins to flourish). I would further speculate that those of us who had initial success with EI followed by problems weren't changing sufficient water, allowing nutrient levels to reach toxic excess. The response of reducing the dosage "some" wasn't good enough for me because I didn't have a clue how much "some" was. Since I hadn't bothered to think the math through, I dumped this method and went looking for something else. Now that I'm "playing math" I'll come back to "some" a bit later.

I've recently switched to PPS Pro (sort of). I'm thrilled with the initial results, but I was thrilled with EI initially too. My tanks were obviously deficient in either potassium or traces and responding well to having that corrected. I couldn't help but wonder if I'd be happy with this method long term, or if I'd have problems down the road. Please note, I haven't read the data that supports this method, I've only taken the recipe. But I am aware that excess potassium and excess traces can also cause problems.

So my next question was, if I can (crudely) predict the levels that will be reached based on what I put in and how much water I change, could I go backwards and figure out how much I should put in based on the water I will change weekly to ensure that I don't exceed maximum target levels for any nutrient. It only took a few moments after actually pulling out some scratch paper to have me kicking myself as an idiot. The formula is simple. The weekly dosing for any nutrient should be the maximum target level times the percent of water changed weekly. The dosing can then be divided into 1 or 2 or 3 or 7 doses per week. This would just serve as a crude starting point. Tanks with high light, high CO2, and fast growing plants will take up nutrients at a higher rate and the dose would need to be modified upwards. Plants with a heavy fish load or that receive generous feedings would need to have the dose modified downward as those increase the nutrient levels.

If my thinking is wrong, please let me know where I messed up. If my thought process has merit, could someone let me know what the target levels are for the various nutrients and which calculator is best to use to decide how much to achieve what level.
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the only flaw I see is that you state that you are achieving 2x by doing a 50% wc, when in essense you should be diluting the solution by removing 50% of nutrient enriched water, and replacing with non nutrient enriched (not accounting for nutrient levels in tap water), so you are at 50% dillution after a water change as opposed to 2x. so in essence, if you dose x nutrients in a week...the most you will reach is x nutrients (plus spill over 50% nutrient levels from week before), assuming of course there is no uptake.

Correct me if I am wrong here...but that is how i took your post.

BTW...as far as targeting nutrient levels, that is in essenxe what pps dosing is. Testing, estimating a bit, testing again, estimating a bit more...etc. until you can dial in nutrient levels with no excess (I think)...i EI dose because I don't have time for testing...lol.
I'm going to use a 2^x number to postpone fractions popping in.

If I dose 16, a water change cuts it to 8 plus 16 gives me 24,
a water change cuts that to 12 plus 16 gives me 28,
the next change takes me to 14 plus 16 gives me 30,
the next change takes me to 15 plus 16 gives me 31 (fractions pop in now)
the next change gives me 15.5 plus 16 gives me 31.5,
the next change takes me to 15.75, but at this point it shoud become apparent that the limiting factor will drive me to a maximum of 32--twice what I'm dosing.

My calculations are based on the forumla for an infinite geometric series with a common ratio of less than 1. Zero water changes would give a common ratio of 1 (the max) and the series would no longer converge. Advocates of zero water changes target nutrient input that exactly equals plant uptake. Otherwise the levels would continue to rise without limit.

You've hit the nail on the head. I don't want to go nuts testing. But I don't want to change 50% weekly either.
So your saying in essence, as time progresses, the dosing should decrease to maintain the same target levels...interesting point. i am lost from here though.
Not at all. What I'm looking for is a level of dosing that ensures I never exceed a maximum level. What that amount of dosing is will depend on the amount of water changed.

Using 50% as an example, I'd be fine if the tank was at 10, but would never want to go over 20. The idea is that I'd always be between 10 and 20. I think the plants are fine as long as they have "some" but not none or too much. If I have an upper limit, the tank will always be under the limit that causes problems.

If I were starting a new tank, the levels would be low initially (probably not a bad thing) and then increase over time (fairly quickly) to the upper limit. I'm also not taking into account nutrients that are in source water. But it seems like that should be a straight in and out (without doing the math). If my source water already has a good level of a particular nutrient, then I wouldn't need to dose that as it would be replenished at water changes. If it had a moderate level, then I'd need to adjust my target level to account for what's already there. If the target were 30 and I had 10 in the source water, then I'd target an extra 20 for dosing. (I'll have to go back to my scratch paper to see if that holds out).

It would be like a logarithmic curve. The levels would initially rise fairly quickly and then level off as they neared the limit. The graph is level (including water changes) with number of doses/weeks along the bottom.

Edit: I played in excel a little. If your water already has nutrients in it, then you'd take the difference between what you have and what you want and use that for a "target" and weekly dosing would be the percent of water changed times the adjusted target. If you dose straight to the target, you'd eventually wind up with the max target plus what's in the source water.

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That 50% WC thing always gets people. It just doesnt seem to be possible It does work out though. If you change 50% of the water a week, you will always end up with 2x your weekly dosing.

What i have found is that you reach that 2x point very fast.....within a few weeks. Very few tanks eat that many nutrients. We have a guy in our club (you know who you are), who doses EI and he actually does eat all those nutrients. He is however, putting mad amounts of light over the tank and his water is SUPER soft....which i believe allows for much easier uptake by plants.

PPS Pro is not a dose and test method, it is actually very similar to the ADA methods. It seems that you use lower CO2 to limit the growth which in turn lowers the need for nutrients. Plants adapt, it seems they adapt to almost any conditions.

Testing - Ok, i am sick and tired of anyone who says "this method requires no testing". There could be nothing further from the truth. I have heard Edward say it with PPS Pro, but guess what, i have seen some limiting issues with higher light and higher bioload. I tested and found this to be true, and adjusted. I have Tom say the same thing about EI. Then in the next breath he will say "i have never said you have to add ALL that stuff ALL the time". The only way to find out is to test. If you dont test you dont know whats going on and you dont excel in this hobby.

Difference between two approaches.

For me it really has come to growth needs. I prefer slow growth for layouts. Its very difficult to do this with EI, so i use PPS. BOTH methods are not all answers. Learn to test and determine your growth goals.

Weakness

EI - A lot of nutrients!!! You do something wrong and you have a ton of algae. I dont care what anyone says I have grown some of my most fantastic algae with EI. You have to pump a ton of light and co2 into the tank to balance the suggested dosing of EI. Dont do this and you will hear nothing but complaints about algae. GSA!!! This is the biggest for me. I have never been able to work with EI without it. I have tried everything.....more PO4, more Co2.....guess what, GSA!!

You want to have perfect growth with EI, test!!!

PPS Pro - One mixture for all. This is not always ideal, especially if your tap has a lot of something already in it. The best way to deal with it is to do LESS % of WC's. There is also the possibility to bottom out nutrients with higher CO2 and higher light.

You want to have perfect growth with PPS Pro, test!!!

I have great luck with PPS Pro, and lower nutrient levels. Most aquascapers do. I have never had long term luck with EI.

You want any luck....test!!!

jB
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BTW...as far as targeting nutrient levels, that is in essenxe what pps dosing is. Testing, estimating a bit, testing again, estimating a bit more...etc. until you can dial in nutrient levels with no excess (I think)..
Math is easy, our interpretations, assumptions, questions we ask, hope to answer are quite another matter.

There is going to be some excess in most all cases as limitations will depending on the severity, cause a reduction in growth. "Excess" is rather a non limiting concentration. Where does excess or a non limiting level become inhibitory?

That's the other side of the graph and a different, but relevant question.
If we know both the high and the low end of range that a water change and a dosing routine produce, then it makes targeting a particular range, or estimating it much more effective. This may be tested(PPS) or use water changes(EI) or a combo of both(older methods such PMDD and the list of levels and parameters). Each produce essentially the same thing.

Regards,
Tom Barr
Sorry for the little outburst of temper. Being patronized always gets my goat.
PPS Pro is not a dose and test method, it is actually very similar to the ADA methods. It seems that you use lower CO2 to limit the growth which in turn lowers the need for nutrients. Plants adapt, it seems they adapt to almost any conditions.
You will also note, ADA and many folks use a lot less light than many folks that curiously have trouble with algae and balancing things............

15ppm of CO2 is fine and was for many when folks used 1.5-2w gal of NO FL's 10-20 years ago. I know. I and many other folks kept plants then

It's when I started seeing how much light could be added and then had to add more CO2/nutrients to compensate...........still....using higher CO2/nutrients with less light provides a more stable tank and system.

Which seems to be what you suggest is a goal.

If things are light limited, which is a much more stable easier to maintain consistent parameter than CO2 or any nutrient is, it makes logical sense to do things this way, but so many folks are not wise to this, they want more light and then try limit other nutrients to slow growth.

That's putting the cart before the horse.

George Booth and I have lamented about this for nearly the last 10 years as well, HLD is the problem and thus places more demands and less stability on CO2 and nutrients.

It all starts with light then progresses to CO2.

Testing - Ok, i am sick and tired of anyone who says "this method requires no testing". There could be nothing further from the truth.
That's nice, I use to think so also, so did Amano, so did Edward, we gave up. You are just not going to get that many folks to do it for all the yelling and fear and loathing you, I or anyone professes. Been there done that. Think about why Edward gave up. Think about why I suggested it and these days rarely do. Think about why most of the best looking tanks seldom if ever are being tested? Work, maintenance and gardening, not testing is what keeps things looking good.

It cost a lot and takes a lot of effort to do it right. Few get into this hobby to test water. Did you? I didn't.

I test carefully to answer certain specific questions so I no longer need to test later.

A good test will allow me a lot of flexibility and not need to test later for that parameter as I've explored it's upper and low ranges independently of other interactions that might confound my results.

I have heard Edward say it with PPS Pro, but guess what, i have seen some limiting issues with higher light and higher bioload. I tested and found this to be true, and adjusted. I have Tom say the same thing about EI. Then in the next breath he will say "i have never said you have to add ALL that stuff ALL the time". The only way to find out is to test. If you dont test you dont know whats going on and you dont excel in this hobby.
Well if you want a black and white method there is not one.
Some tweaking is required, however test kits are not required unless you consider the plants "test kits". I've always used them with test kits.

PPS is lighter/leaner, so that;s to be expected, EI is richer for the higher light tanks and if rather than quoting me, read the dang article, it clearly says that you can back off till you get a negative response from the plants, PPS and ADA can also be used in a similar fashion, coming from the other direction add a bit more till you no longer get a positive growth response.
However ADA also adds a lot of nutrients to the sediment as well. So while lean is some parts of the tank, it's rich else where. PPS and EI are independent of that, but can work well synergistically with a rich sediment.

You can start at a lean level and move up, or a rich non limiting level and reduce it slowly till you see a negative response then bump it back up.
All you need is a decent observation skill set to watch plants.

Put another way:

Test kits do not measure plant health, nor algae presence.

Some user common sense and assumptions therefore must apply to test kits and their use, much like dosing... much like keeping a planted tanks and gauging the plant health and responses.

There's a lot of room for mistakes in there....and that is how we learn.
Which is not a bad thing.

Difference between two approaches.

For me it really has come to growth needs. I prefer slow growth for layouts. Its very difficult to do this with EI, so i use PPS. BOTH methods are not all answers. Learn to test and determine your growth goals.
If you seek to manage growth and slow things down, use less light. That's where growth starts, or perhaps you believe it starts somewhere else? CO2 or nutrients?

Not only will less light slow growth, it'll also place less CO2 demand and allow the plants to better utilize nutrients since there is less CO2 stress. Maybe Tropica, Troel and Ole are also wrong. Maybe Kasslemann too.
Everyone that suggest lean levels also has less light curiously..........or does not measure nor know their light values.

Light is far more stable than CO2 as far as our management is concerned also.
So that's 2 very big advantages to providing a nice stable slower growth tank.

I have no trouble with slow growth tanks and EI, I dose less due to common sense, I know I really do not need that much(traces cost more \$ since I use TMG etc), however, since I tested things, I also know that independently, higher levels of K, PO4, NO3, traces also do not cause algae nor other issues.

These tanks get no algae and run for years. Having induced a number of species of algae over the last 10-15 years, that allows me to know what is the problem with my tanks, as well as others.

Many folks swore up and down they had everything right, then they added more, say CO2 and Mike ended up with 220 ppm of CO2 and fish where fine etc.

All because he believed strongly in a test kit and method rather than plants, watching things etc.

Algae don't like nor do the plants, test kits can and do.
Living things are far more integrative.

Lower light and rich nutrients/CO2 is easy as pie and much more stable than higher light tanks, this is nothing new, I've been telling folks this for nearly a decade and so has George and Karen and others.

Algae grows slower, problems happen slower so you can catch them faster when you have less light.

EI - A lot of nutrients!!! You do something wrong and you have a ton of algae.
If you have a lot of light and you mess up CO2, yes, then you do.
If you have low light, then no.
CO2 and dosing are less critical in every method and set up when you address stability and growth rates as the light intensity is reduced.

That's common sense.
You make little mention of the relationship with light intensity here.

Since you profess testing with passion, perhaps you might give some data about light in plant useful units and measures?

You test CO2, folks have had a lot of troubles measuring that anyway as we have long known.........and you test NO3 and PO4 and K and Ca and Mg using standard calibrations?

Let's not even bother with the trace metals............

You have yourself a lot of work to make heads or tails of things and that assumes nothing went nutty during your test.............

This not something I do 24/7 for years, I do it for a few weeks to see.
Then when my question has been answered, I repeated it to make sure I did not do something wrong or overlooked something.

I'm human and know enough to recheck myself and look for obvious.
You have to, to get the answers.

Limiting factors can cause all sorts of problems, that's why I wisely chose a higher non limiting approach rather than a limiting approach like ADA/PPS/PMDD.
I can prove without a doubt that these things are not causal agents, they on the other hand cannot show otherwise. Thus they cannot possibly be correct.
Simple process of falsification, you test your hypothesis.

If you are not willing to do so, then you really cannot do any more than mere speculation.........and there's enough of that in the hobby as it is...........

I dont care what anyone says I have grown some of my most fantastic algae with EI.
I can as well, I remove the CO2 and add lots of light.
Does that surprise you or something?

You have to pump a ton of light and co2 into the tank to balance the suggested dosing of EI.
Again, you missed the light part.
You do not have nearly the same CO2 demand at 80 micromols as you do at 450 micromoles of light. Why don't you critically measure this and see since you love to test to find out?

I have.
I know.
I tested it.
If you want to prove this to yourself, you need to do so.
Otherwise it's all speculation and you really are just guessing.

Then you'll know.

CO2 is extremely ephemeral. It can change dramatically in 30-60 minutes in our tanks, flows, shading and all sorts of other factors come into play here.
The existing test methods are poor. I developed my own based on a pH probe and KH reference solution and gas membrane. Compared to the IR, it's about 0.1ppm accurate for a 5 minutes reading.

Took a lot of work, but it's far better than another else's test method in the hobby.

I have tried everything.....more PO4, more Co2.....guess what, GSA!!
Methods do not fail, we do.
PPS works well, so does aDA, so does EI.
There are examples of each that are lacking GSA.
I have done each of these methods as well as several others including marine methods.

Just because you failed and want to blame a method does not mean it's the method's fault.

I chose to try and figure out what I might have been doing wrong when I initially had issues with PPS.

Like many that started using it, I had some BBA and other related issues.
I focused on CO2 and the issue was resolved.

It was not the dosing however, it was the poor use of CO2 for myself and most of the folks using the method.

You want to have perfect growth with EI, test!!!
Oh come now, you know there is a lot more to perfect growth than dosing, it involved a lot of maintenance, filter cleaning CO2 etc.

You are guilty of doing the same thing that you critiqued these methods about. Suggesting that perfect growth will be achieved with test kits alone.
Not everyone needs to test to have a nice scaped pretty tank, maybe you do. But others clearly don't and thus this cannot possibly be a cause for perfection vs someone who doesn't test................

PPS Pro - One mixture for all. This is not always ideal, especially if your tap has a lot of something already in it.
Well, I could say the same about EI or ADA as well.

The best way to deal with it is to do LESS % of WC's. There is also the possibility to bottom out nutrients with higher CO2 and higher light.

You want to have perfect growth with PPS Pro, test!!!
Or simply dose more and do large % water changes.
Fast + simple and folks are already well aware of the fish health benefits and load increases that they can have with frequent water changes and the lower cases of disease.

Helps fish, reduces the need to test and can benefit planted tanks a great deal.

Are frequent water changes bad for non planted fish only tanks or something?

I have great luck with PPS Pro, and lower nutrient levels. Most aquascapers do. I have never had long term luck with EI.

You want any luck....test!!!

jB
If you want to really understand a method, you need to consider the other variables beside dosing. Light and CO2 and their measure.

You spent all this time pressing the virtues of testing and really never talked about the 2 main issues.

If you seek to understand a method and be successful with it and master it, rather than just winging it and hoping, you should go back and keep trying and testing until you do have success. Since testing and learning are your a large part of goals it appears.

Regards,

Tom Barr
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I'm going to use a 2^x number to postpone fractions popping in.

If I dose 16, a water change cuts it to 8 plus 16 gives me 24,
a water change cuts that to 12 plus 16 gives me 28,
the next change takes me to 14 plus 16 gives me 30,
the next change takes me to 15 plus 16 gives me 31 (fractions pop in now)
the next change gives me 15.5 plus 16 gives me 31.5,
the next change takes me to 15.75, but at this point it shoud become apparent that the limiting factor will drive me to a maximum of 32--twice what I'm dosing.

My calculations are based on the forumla for an infinite geometric series with a common ratio of less than 1. Zero water changes would give a common ratio of 1 (the max) and the series would no longer converge. Advocates of zero water changes target nutrient input that exactly equals plant uptake. Otherwise the levels would continue to rise without limit.

You've hit the nail on the head. I don't want to go nuts testing. But I don't want to change 50% weekly either.
And the math is correct.
A simple solution is to simplify the water change. Then you still get the services you desire, no testing, and far less labor. Several members here in the club have long added their automated water change systems going back, maybe a decade.

Many breeders and and fish only folks have also long thought up clever ways to reduce the labor, python water changers remove the buckets.

But this brings up an interesting issue. Fish only folks long use water changes to maintain good fish health and reduce diseases. Discus folks and folks with high bioloads also will attest to this.

Now we can reduce that by adding plants, or having less bioloads, that is a trade off though...............

The plants might be an added benefit.
But if we are simply using plants to reduce water changes via uptake, then a plant filter using emergent plants may be much more appropriate.

No CO2, no test, easy to care for.

Or a non CO2 tank approach.

But if you want no work, no water changes and use CO2 and have finicky stem plants, now you are starting to paint yourself into a corner.

Some simple changes, some plant species changes, reduced light etc, non CO2 etc can achieve that goal very nicely and be far more resilient than EI, PPS, PMDD or ADA.

I think most folks can use a lighter version of EI or a heavier version of PPS/PMDD and tweak things a bit to change say 25% week or 50% every two- 3 weeks etc. A good eye etc will help. But it's sort of like the dentist, do you brush 2x every day, or once every 2-4 days and go get a few cavities filled? You cannot really over do the water changes, 2x a week at 50% and dosing well afterwards will produce better growth, health and a cleaner tank.
It's more work, but there's not any scaper that will tell you that there is not a lot a work involved in producing a nice looking tank.

What makes me wonder is why not go all the way if that(few/no water changes) is your goal? No water changes for a year, very stable systems etc, why even bother with CO2 at all? It increases the growth rates 10-20X faster, that means more pruning, algae like CO2, more work, having to add CO2 which as some suggest NO3 or PO4 levels are pollutants, more folks kill fish using CO2 incorrectly than any other cause in the planted hobby today.
You and I and everyone on this board knows this yet many still support the use of CO2 enrichment...........

Thus the arguments are much more for non CO2 methods than the EI, PPS, PMDD, ADA methods if few/no water changes and fish health are concerned.

I'm curious as to the rational that folks use to promote dosing routines when they do not address Light first, then CO2 second. Those are common sense approaches to management for reduced growth rates and reduced maintenance and water changes.

Tell you what, try the non CO2 approach. Then you'll see and realize no testing, no water changes, nice manageable growth, very stable system.
These tanks are easier to care for than a fish only no plant tank. Evaporation loss is the biggest labor issue.

I think Diana is the person that really supported this method, no water changes and the arguement, not PPS. George Booth really supported his contention for lower light and that all these folks using high light are running into issue with CO2 and nutrients due to increased uptake.

These are old ideas and have been discussed many times in the past, perhaps not by you or this group of folks, but nonetheless they have. And likely will many more times.

When you go non CO2, you have such low rates of nutrient demand, that dosing is hardly critical at all.

So it really gets back to the rates of growth.
Slower rates= easier to maintain, fewer water changes.

Try these things out, try coming up with a simple water changer/routine etc. Do not create a barrier where none exists, we are creative enough folks to figure a way around added labor there.

Try a non CO2 tank out.

Try changing plant species that take less work to tend to.

Try reducing the light levels, I see folks claiming you need 4 w/gal of PC lighting to grow Gloss every week or month on the boards, that's simply not true and never was/has or will be. You can test it and see also.
I have grown it as have many folks in our club in very nice health at 1.5-2.2 w/gal with plain old T12 FL's, or about 40-120 micromols of light. Not much and that's at 24" tank in the 2.1 w/gal and 1.5w/gal was a 16" depth.

Regards,
Tom Barr
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my eyes are burning.
my eyes are burning.
Haaha. I read this entire thread yesterday night at 3:30am. My head still hurts from it...so many things to consider...brain...fart.

Very informative though. Thanks everyone.
3
My thought process was triggered by seeing yet another EI fan complaining of algae, stunted growth, and high levels when testing. Even though I'm showing these graphs, I won't use EI again--it nuked my own tanks. I just couldn't help but wonder why. I've switched to PPS Pro (slightly modified) and so far am thrilled with the results. After having been burned with other ideas that have swept the forum, I'm nervous about getting to excited about PPS Pro just yet.

Jason is absolutely correct when he says there is no substitute for testing. Every tank will vary in the nutrient uptake rate of the plants (based on numerous factors), and the waste load produce by fish and excess feeding. I'm just trying to understand/quantify things so that I can postpone intervals between needing to test and needing reset the levels in my tanks.

I'm using 20 as a target level as that seems to be the current "hot number." My personal opinion (at that means that no one else has to agree) is that is too high a figure for a modestly driven tank and doesn't allow enough wiggle room for increases in levels due to fish and feeding.

I'm attaching 3 graphs--I think it makes it easier to see the levels I'm discussing. Once again, I can't quantify the load produced by the fish or the uptake rates of the plants--that varies from tank to tank. The only way to know what's happening a particular tank is to test and adjust based on the results.

The first graph shows what levels are reached based on the amount of water changed. If you fudge a little on your water changes (and that includes forgetting to tank into account water that's part of the system but outside the tank in filters), the levels rise higher. I've also shown what happens to those who prefer more modest water changes (I would never advocate zero changes), even if the dosing is cut in half as was suggested.

The second graph shows what happens if your source water already contains measurable levels (that's called testing) and dosing doesn't take those levels into account. I randomly selected a source water level of 10. The adjusted dosing would be the target of 20 minus the source of 10.

The third graph shows the accumulations if the dosing is adjusted to the percent of water changed. I find it interesting that if the dosage is adjusted to smaller water changes, it takes longer for the tank to level off. I think the charts make it possible to predict how long it will take before a tank approaches levels where testing should be done and the tank reset if needed (through several large water changes to drop levels)

EI fails to address varying levels of water changes and also fails to address nutrients that are present in source water. I'm well aware that it works well for many. I'm just trying to understand why it also fails for so many of us.

For those who've failed with EI but would like to keep trying to make it work, I'd suggest dosing (the level required to achieve your target for the entire tank) times (percent of water changed weekly--no fudging and estimate low to postpone having problems). To allow wiggle room for fish waste, etc. in a modestly driven tank, I'd reduce the target level. I'm hoping that by the end of the summer I'll still be saying PPS Pro rocks and then I won't have think about any of this and just test once in a while to be sure my levels are still reasonable.

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If the tap has 2ppm of PO4, then adding more PO4 is not going to hurt not help. The different between having say 2ppm vs 4ppm does nothing to a tank.
You are welcomed to try and show that it does.

For NO3, a similar issue exist.
So the tap is really much less of a factor.

When the tap is low in GH, say Mg, then Gh booster helps, having excess Mg or NO3 is not going to harm anything unless you get very far outside the ranges. So that begs a question, what are those ranges?

Is there a an algae difference between 20 and say 40ppm of NO3?

None that I've ever measured. All you have to do falsify and investigate the upper ranges while maintaining a stable non limiting level for the other potentially confounding levels.

And that's where folks can have troubles.

People use to say that high levels of PO4 caused all sorts of algae.
So we simply added it to see if it was the root of the problem as folks said. Instead, we had more plant growth.

Same deal with NO3, we added it and it yielded the same results.
No algae, but also no added plant growth. Both where non limiting for plant growth.

This disproves the notion that your problem with the method was due to dosing, it does not however, suggest why you had problems or other folks have problems with EI, PPS, PMDD or ADA.

There is no method that will yield no problem or algae issues. Which is what you are suggesting. The same might be said for ADA, PPS and PMDD as well. Folks are human and make mistakes. We assume that we cannot be wrong about our CO2 or other parameters. We all over look things.

All we have to do is look at the tap water report to get an idea. Many in Europe do not add KNO3, instead they use K2SO4 since their tap has 40ppm of NO3.

A 50% change adds 20ppm and some fish waste keeps things going well for NO3.

I do not think PPS, PMDD, nor EI suggest not looking at the tap water sources, nor do they suggest that the fish load is not a factor.

Fish load is producing NH4, not NO3 directly, unlike our dosing routines.
That compares apples and oranges, NH4 is far more toxic and can be tested to see if it produces algae blooms or not vs NO3. That can be a large variable in a typical person's routine. If you have kept discus you know that they need large frequent water changes as does any over loaded tank, EI's suggesting a larger % water change based on that as well. It exports NH4 and organic N that will turn to NH4.

It's not all about NO3, which is much less toxic than NH4.

By over loading any dosing method with fish, but not exceeding a NO3 range pre set, one may still get algae blooms. I've done it to test if this was true or not. And you can bet you see a much higher incidence of algae blooms, green water and Compsopogon and BBA etc.

One assumption that folks often make is that excess levels are "bad".
That well may be true.

What is meant by excess levels? Non limiting? Toxic? Algae blooms?
At what level does the nutrients cause such issues?

At what point does it induce algae, cause plant health issues that we can safely say is due solely to that one isolate nutrient?

It might be a good idea to see for yourself and prove it to yourself.

Obvious each method can and does work well, why you personally had issues and other did not is not the method's fault per se, if I failed and saw someone else did well with a method, I know it was my fault, not the methods.

Many folks do very well with non CO2 planted tank, but have troubles when they add more light CO2 etc, based on some of the arguments here, that would suggest that adding CO2 and more light merely cause algae and that those are bad methods.

But we know that is not really true, but from their non CO2 perspective, it most certainly would appear that way.

Regards,
Tom Barr
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In the interest of being fair, I'm running a graph for PPS Pro too. If my data is incorrect, please let me know. Digging over at APC gives me that PPS Pro doses 1 ppm of nitrate daily which makes 7 per week.

I can see I either need to bump my water changes a little or scale back slightly on dosing if I want to prolong periods between needing to test and reset my levels.

Once again, the horizontal axis is the number of weeks. The vertical axis is the level reached.

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I have to publicly apologize to Tom for misrepresenting his dosing.

I mistakenly used a dosing level of 10 ppm per week rather than 10 ppm 3 times per week, which makes 30 per week. The corrected graph is below. I've shown what happens at a 50% change. I've also shown what happens if you fudge a little on your water changes and only do 40% (since we all fudge a little sometimes).

The horizontal axis shows the number of weeks. The vertical axis shows the levels reached.

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I don't know what it is about summer. When it's hot during the day I can't stay awake. If it's hot at night I can't sleep. Since I'm up, here's one last comparison--phosphates.

The first chart is for EI. I've include a 40% water change again since we all fudge sometimes.

The second chart is for PPS Pro. Since it doesn't have a required water change level, I've included several amounts. I didn't include no changes because I do believe in changing water (just not 50%)

The horizontal axis is the number of weeks/water changes and the vertical axis represents the accumulation of phosphates.

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Chart no# in the last post is a nice example. Thanks for putting them together here.

The issue of how a water change influences a dosing routine and the trade offs involved is a hot subject and has been for the dawn of web based disscussion.

We kicked this one around for years in the SFBAAPS club, they'd namely all moved to ADA routines with sediments and dry or liquid dosing, and stuck with ADA and EI suggestings of 50% weekly and start up WC being at every other day or 2x a week 50-60% or every 5 days etc.

A few of us suggested 25% for many years and I think that is a good medium based on plant observations of various picky species.
Jeff Kropp had tried no water changes and was never able to tweak things to get the ideal responses he desired.

Dave Gomberg of course never did any water changes with 2 tanks for 2-3 years(this was about 10 years ago). He killed his fish with too much CO2, but never had algae, never had other plant related issues, just was a fish killer

Alan, this guy was even lazier and wanted to get away from water changes so he went automated. Very very cool. Also got rid of massive BBA issues in a very very over stocked low light tank with 3 fire eels as large as a good size person's arms. I think he fed 1/4 pound of food daily, to 180gal.

Very well thought out approach.

The point is to have many club memebers locally try these things out for yourselves, see what trade offs, what options and what results you come up with and what seems the best for you.

Large water changes are easy to do a "factory reset", so they make a nice default. Good test kits are also critical.

Models help give you a good idea and the theory.
Adding that to practical testing of the model allows you to tweak the model better for each individual application
(eg. tank, point in time on that tank-that changes also).

Then you adjust the model and tweak it further.

You might measure the food and do a simple jar test to see how much N and P come in from food on an average day. You can then add that to this model.

Assume 10% of the food is used for the fish and you are off.
Add tap water to the model and now you have the 3 main inputs.

Balancing outputs is also very useful, but not that practical for hobbyists.

Assuming that the N from fish food/waste is the same as NO3 dosing might make the model simpler as long as the N sipply from the fish food is relatively small, plant biomass and growth rates are high.

I think it'll be an issue if you have more than say 1 adult discus per 10-15 gallon and on tanks 50 gal or higher. In general, planted folks with hig biomass tend to be fairly reasonable in their stocking habits.

Still, this can give you a simple hobby level method to estimate the N and P from fish to add to the model.

I might do this for Brine, several general types of flake and a few frozen foods, maybe baclworms/live brine also.

Then folks could take the fresh weights from those, much like we use for KNO3, and get a close estimate of fish based nutrients in the system.

I have the lab to measure such nutrient contents from the fish/foods etc.
When I do the next set of nutrient analysis for some sediments, I ought to run a few of these.

It's a PITA to run these machines, but once set up and running, I can run 100's of samples relatively easily.

Regards,
Tom Barr
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CherylH:

When thinking about nutrient levels, you need to put all the things that produce nutrients in column A and all the things that consume nutrients in column B:

Nutrient production "A"
Fish waste
Nutrient dosing

Nutrient removal "B"
WC
Plant uptake
Filter capacity

It is entirely possible to be dosing an arbitrarily large amount and still run the nitrate etc to 0 due to plant uptake.

Please measure the nitrate 10 minutes after a dose and 10 minutes before the next does to APPROXIMATE the total uptake capacity. :icon_smil

I don't know what it is about summer. When it's hot during the day I can't stay awake. If it's hot at night I can't sleep. Since I'm up, here's one last comparison--phosphates.

The first chart is for EI. I've include a 40% water change again since we all fudge sometimes.

The second chart is for PPS Pro. Since it doesn't have a required water change level, I've included several amounts. I didn't include no changes because I do believe in changing water (just not 50%)

The horizontal axis is the number of weeks/water changes and the vertical axis represents the accumulation of phosphates.
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