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How do you dose ferts without measuring them first?

3K views 18 replies 9 participants last post by  herns 
#1 ·
I'm a bit of a scientist type, so it bothers me to dose a tank without measuring and knowing how much of something I'm starting with. Do people measure their tanks for Ca, Mg, Fe, etc.? If so, are there test kits out there? If not, how do you know what and when to dose?
 
#2 ·
While there are test kits out there for the various elements that plants require, sometimes the cost of the test kit is not justifiable.

For example, we know that plants require CO2, and there are CO2 sensors available, but they cost in the thousands of dollars. That kind of price is not justifiable (to me, anyway).

To answer your question about dosing, Tom Barr designed the EI (Estimative Index) method of dosing to provide an abundance of nutrients to plants so that they are never deficient. A 50% water change on a weekly basis resets these nutrients to a lower level such that a dangerous level is not accumulated.
 
#6 ·
Great to have your input, Tom.

You are right, too often do we (myself included) say that shrimp are sensitive to heavy metals, etc, but it is all anecdotal evidence and not factual evidence as you have provided.

I myself have not noted any problems with shrimp deaths from EI dosing either; more often than not, I find my CO2 to be the leading cause of shrimp death :icon_redf
 
#9 ·
I actually do not KNOW at what level a SSS grade CRS might die due solely to Cu at a certain ppb/ppm level. There are many other factors that are dependent.

Temp, other livestock, other sources of stress/nutrition etc. So while say 0.08 might not kill them, it may reduce the brood production(never tested this) and might contribute to other stresses leading to mortality.

But these are speculations and should be viewed that way. They might be correct, but someone needs to demonstrate that with some certainty.
Fear is not a good method to rely upon.

We ALL do it(fear mongering) to some degree. But just being aware of the issues is much more helpful it would seem to me.
 
#10 ·
Shrimp make excellent models for aquarium toxicity in Freshwater systems. Since they breed like flies, and we often cull out the weaker color forms, we have ample test subjects.

They are like the canary in the coal mine.

So a biological assay test, the shrimp become the "test kit" and the plants, algae etc.

I'd rather folks spend time on on the goal; nice fish/shrimp and nice plants, rather than the testing methods. Who got into this hobby ot measure pH and NO3? I've not met anyone yet.

They have uses to be certain.

But often(more than not), folks end up with inconclusive results, or results that cannot be correct due to test errors, no standards to compare to.
It's ironic because I have a lot of experience with testing and methods.

But often the advice based on what the goals are for hobbyists, goes towards not using the test kits. A good old water change is often much more benefit.

If you use the graphing modeling calculator(based on infinite series dilutions), you can still get plenty of Science and predictable outcomes. You target a range, not a specific ppm. In reality, plants, fish are able to do quite well in a variable environment and even if you test and dose carefully, there will still be a lot error associated with that.

In other words, you gain little in spending the time testing a great deal.
Most test a little while, then perhaps only when something is wrong, and not much otherwise. So most of aquarium management is Social/human, not Science issues.
 
#8 ·
It depends on how great a detail you want to get into, but lab quality testing equipment is available, or you can send off plant tissue samples for analysis.
For most hobbyists, though that sort of attention to detail is going way overboard.

You can present the info as a chart or graph with the level of a particular element on the left, and plant growth across the bottom.
At the far left is zero dosing. No detectible level of the thing you are testing.
Plants will die without that element.

Moving slightly to the right there are low levels of something. Barely enough to help the plants out under low tech situation. This low level of the element in question leads to deficiency in a high tech tank when the plants are more demanding. The plants may grow slowly.

In the middle of the chart is a very wide band of 'acceptable levels'.
Plants will grow just fine. There is enough of the element present to supply all its needs, not so much that it will inhibit the uptake of something else, or be toxic to the plant or livestock.
It is this band that Tom aimed for when he worked out the EI method. Dose all week and gradually get more and more nutrients in the tank, but do not get too much. Then a water changes takes it back to the right, almost at the edge of deficiency. The line representing plant growth is level throughout this range. As long as the minimum needs are met there is not more growth with more fertilizer.

Farther right than that is excess. The element may be toxic, or it may competitively inhibit the uptake of some other element. The line representing plant growth is usually growing down at this end of the graph. If some one element is present in near toxic levels there may be ways to deal with it, for example growing the plants faster, then trimming. The trimming removes that element from the system. Better not to get into that situation by dosing anywhere in the safe range, not at this high level.
 
#11 ·
I'm a bit of a scientist type, so it bothers me to dose a tank without measuring and knowing how much of something I'm starting with. Do people measure their tanks for Ca, Mg, Fe, etc.? If so, are there test kits out there?
Yes there are, some may be debatably worthwhile. Some are pretty questionable. Bear in mind, these are "hobby" test kits, not lab grade. You can improve accuracy by creating known solutions and comparing.

If not, how do you know what and when to dose?
Most people get in the hobby to grow plants. Testing gets pretty redundant quick after you realize how big the targets you are aiming for are. If you are adding ferts, you probably have enough. IMO, It would really take a special level of ineptitude to actually have too much. Of course some would argue with me that the tolerances are finer then I believe.

Moral of the story, testing isn't that important, but if it makes you happy. Go for it. :)
 
#13 ·
Thank you for all the responses. I certainly am not in the hobby to test! As I've mentioned in other posts, I'm new to planted aquariums, so I'm still learning how it all works. With my pond I've never tested anything -- just dug a hole, filled with water from the hose, and let things move in on their own (I even have little minnows in there somehow!) And with my saltwater tanks I would only test for the first month to see that the tank was cycling properly, and then once every several months just to make sure that everything was still normal (although I think I've always been able to tell if something "bad" was going on in the tank based on the behaviors of the critters and growth of the coral).

I read the EI explanation here:

http://www.barrreport.com/showthread.php/62-The-Estimative-Index-of-Dosing-or-No-Need-for-Test-Kits

and if I understand it correctly, I'm looking at weekly 50% water changes and dosing forever. And that the dosing will be highly dependent on the level of light you have in the tank, which is hard to determine accurately without an expensive PAR meter.

Since I didn't get into the hobby to test, change water constantly and spend money on fertilizers, I guess more to the point of my question is whether dosing is necessary at all. I read Walstad's book, and in the chapter about plant nutrition she concludes that a low-tech tank with a soil substrate doesn't need water changes or the addition of fertilizers since many of the nutrients/micro-nutrients come from the soil and are replenished to a lesser extent by the addition of fish food. I realize it's been many years since she wrote that book, and that some of her conclusions may have changed since then, so I wonder if this is one of them.

Thanks again.
 
#15 ·
T And with my saltwater tanks I would only test for the first month to see that the tank was cycling properly, and then once every several months just to make sure that everything was still normal (although I think I've always been able to tell if something "bad" was going on in the tank based on the behaviors of the critters and growth of the coral).
Since marine salt mixes cost and take an addition step to mix, many use test kits to avoid cost and mixing hassles. FW folks do not have this issue for the most part.

I still do large water changes and KISS for marine systems. One added cost/step vs all the other stuff to avoid it.

I read the EI explanation here:

http://www.barrreport.com/showthread.php/62-The-Estimative-Index-of-Dosing-or-No-Need-for-Test-Kits

and if I understand it correctly, I'm looking at weekly 50% water changes and dosing forever. And that the dosing will be highly dependent on the level of light you have in the tank, which is hard to determine accurately without an expensive PAR meter.
No, 50% is entirely arbitrary.
You can chose whatever % or frequency you chose, if you increase the frequency or %, the error associated with the range will go down:

95% 2x a week water change san ddosign thereafter: likely within a very tight range of small error.

If you do 20% once a month, then the error will increase a great deal.
Wet's dosing calculator and graphing function lets you explore those models and scenarios.

http://rota.la/ei/

Another misconception:

http://www.barrreport.com/showthread.php/4882-Confusion-about-EI-and-other-myths

A simple method to reduce the % water changes and dosign:

http://www.barrreport.com/showthrea...I-can-get-you-there-with-a-small-modification

Since I didn't get into the hobby to test, change water constantly and spend money on fertilizers, I guess more to the point of my question is whether dosing is necessary at all. I read Walstad's book, and in the chapter about plant nutrition she concludes that a low-tech tank with a soil substrate doesn't need water changes or the addition of fertilizers since many of the nutrients/micro-nutrients come from the soil and are replenished to a lesser extent by the addition of fish food. I realize it's been many years since she wrote that book, and that some of her conclusions may have changed since then, so I wonder if this is one of them.
Thanks again.
That's works well for a non CO2 approach, I dose once a week to the water about 1/10-1/20th EI and forwent the soil sediment. I do no water changes.
They are very different goals, no method will be all things to all hobbyists' goals.

Some have different management, CO2 drives growth 10-20X faster than non CO2, there's no CO2 competition between species of plants(so you can grow them all together, in non CO2 tanks, you really have a very hard time growing several species well together, most are "easy" weedy species). A well maintained garden and lush landscape is much harder to do, but it can be done. Most lack the patience frankly.

All methods grow plants, the difference is at what rate. EI is mostly a simple method to rule out limiting factors due to nutrients for any light amount. CO2 is still dependent no matter what method you chose(except the non CO2 method, but even there, CO2 limitation plays a defining role)..
 
#14 ·
Low tech tanks and high tech tanks have one concept in common:

Supply the plants with the nutrients they need in quantities that work. The target here is like hitting the side of a barn.

With both systems you have a starting point:
Tap water- Read the report your water company produces, or have your well checked- remember the problem Diana W had with zinc. If you know the water varies, then test that before each water change.
Substrate- If you set up a reasonably rich substrate with good CEC then fertilizing is a lot easier. The substrate starts off the tank with reasonable levels of most things, and before it is exhausted you are dosing to refill it.
Fish food- If you have livestock, and are feeding them this is a good source of most nutrients for a low tech level of tank. Not enough for a high tech tank. I found that my heavily stocked tanks were short on K and Fe first, as well as C. Those were the first things I started dosing.

If you find that contributions from these sources are plenty then do not dose more of that element.
If you find the supply of something is anywhere near the bottom of what will work, then dose it. This is common to both high tech and low tech tanks.

For low tech tanks 'dosing' might simply be a water change once a month. Or maybe it does involve adding fertilizers or carbon.
For high tech tanks it probably means dosing pretty much all the nutrients.
EI is one method of dosing. It hits the 'side of the barn' target just fine, then clears the tank of excess weekly. As you get to using the system you will adjust as needed. You might look at test results to see if you are using too much, or you will look at the plants to see deficiency. When I started using it I still had heavily stocked tanks, so I adjusted the KNO3 way down, but had to add KH2SO4 in large amounts. Now that I have a lot fewer fish I am swinging back the other way.

Here is how I decided how much to use:
Macros:
N- based on NO3 test.
P- I have a phosphate test, and it shows a little color. Before I had the test I equated the P with the N. If fish food was supplying lots of N, it was also supplying lots of P.
K- Holes in the leaves show up when I skimp on the K. New growth comes out without holes when I dose more. My K test is the plants.

Secondary:
Ca, Mg: Tap water has plenty, per GH test. Add Seachem equilibrium or Barr's GH Booster for hard water tanks, but this is for the fish, not the plants. Plants never took so much Ca or Mg that the tests showed a difference. When I dosed GH per EI recipe the test climbed. My assumption: Fish food and water changes supplied enough Ca and Mg.
Fe: This is one of the first things I needed to dose even running low tech tanks. So I keep on dosing a little extra with the CSM+B.

Micros:
Dose CSM+B per EI. and I know there is plenty of everything except, maybe, iron.
Somewhere I read dose micros, but just test for Fe. When the Fe tests in the right range, assume the rest of the micros are OK. This works as long as your substrate or water does not have weird levels of something. My Fe test never showed me any color that was on the chart. It was so obviously green, when the chart when through grey and red. So I went back to looking at my plants. They were rich green, and the reds were as red as my low light would let them be.
 
#16 ·
Thanks Diana and Tom... extremely useful information. Sounds like I need to observe, experiment, learn, repeat. :smile: Looking forward to delving into the planted tank world.

Last question -- in your experience can LFSs test micro-nutrients if you bring in a sample? Or are they likely to have only the "standard" tests (pH, PO4, NO3, etc.)?
 
#18 ·
Mostly they (stores) do not have those tests, but call and ask.

If you want to get into testing those parameters, get the kits yourself. There are enough materials in them for you to run quite a few tests, and by the time the test kit expires you will have all the testing you want to bother with.

Testing is interesting to about one test kit worth of reagent.
Then quit.
I got quite a good handle on how my tanks were running that way, then switched over to the much maligned test strips. They test most of the things I wanted to monitor, quicker, cheaper than the test tube/reagent tests. And I know how to interpret them for my water. So when that one pad turns some odd color that is not on the response sheet, I know what it means.

And the plants are still there, live 'test strips' always ready to be 'read'.
 
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