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High nitrate questions

17K views 160 replies 34 participants last post by  plantbrain 
#1 ·
I havent done any testing of my tanks in forever but I was testing nitrate in my shrimp tank last night and decided to test some of the other tanks at the same time.

The shrimp tank had no measurable nitrates---good.

The 29 gallon tank with EI dosing and Aquasoil and CO2 with T5HO lights ( 3 x 24W ) had very high nitrate readings---dark red on the API scale ( I think it said 100--but it was the highest reading )

This is the dosing I use--I add 1/16 tsp of epsom salts when I dose micros ( CSM+B ) I use Green Leaf dry ferts

20~40gal
50% H20 change-weekly
1/4 Tsp-KN03 3x a week
1/16 Tsp-KH2P04 3x aweek
1/2 Tsp-GH booster once a week
5ml or 1/16Tsp-Trace 3x a week
Optional
1-2ml-Fe/Iron 3x a week

Its stocked with 13 Harlequin rasboras, 5 three line corydoras, 3 red clawed macro shrimp ( one that is VERY berried ) and 2 fat otos.

This tank has always been a nightmare for me to keep algae away. Currently I have brown algae everywhere, green dust on the glass and green spot algae on some crypt leaves. I recently upped the lighting to the current levels. Before, it had 2 double strip T5NO fixtures. The brown algae is new, the others have always been present--along with BBA from time to time. None of my other tanks have any algae to speak of. I thought I would try to put the plants in overdrive and eat up the nutrients. Obviously with this much nitrate the plants arent using it all.

I use the same tap water to change the water in the shrimp tank as I do this 29 gallon. I changed the water last night and Im gonna skip the KNO3 this week and check the nitrate before the next water change. I honestly havent tested for nitrate in the tap, but if the shrimp tank tests at zero I would think the tap is close to that. I do have a lot of floating plants in the shrimp tank to keep the water clean though.

Any additional thoughts?
 
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#12 ·
Excessive light will cause algae blooms.
^ this

I'm no expert, but i think light is the problem. I follow the exact same dosing regimen as you do on my 20 Long. I've had a battle with algae for a long time....actually gave up on BBA and decided just to coexist with it.:icon_conf.
The only thing I cut back on was my photoperiod from 12 hrs to 8 hrs. Everything else stayed the same(water changes, Ferts, CO2, etc). This solved my problem....well at least there is only BBA on my driftwood now. Before I had staghorn algae everywhere and BGA on the glass.

There's a part of my tank that gets very little light...as you can see there is NO algae at all on the part of the driftwood that gets little light....And a bunch on the part that is under direct light.



Algae free :hihi:

 
#4 ·
I have the same setup as you do: 29g with 3 24w T5 HO lights, aquasoil with a light stocking of 8 danios. The only algae I get is a little gsa on the glass when I overfeed.

The difference is that I don't dose nearly as much as you do. Only K, micros and iron are dosed in small quantities on a regular basis. Excessive nutrients, particularly N and P CAUSE ALGAE. This website is perhaps one of the only places where people are naive enough to keep on dumping in massive amounts of ferts despite having algae issues.

I would recommend you give your filter a good cleaning, do one extra large water change and only dose K and micros for a week or two. Keep your lighting the same, but cut the photoperiod down by an hour or two until you get the algae under control.
 
#6 ·
The difference is that I don't dose nearly as much as you do. Only K, micros and iron are dosed in small quantities on a regular basis. Excessive nutrients, particularly N and P CAUSE ALGAE. This website is perhaps one of the only places where people are naive enough to keep on dumping in massive amounts of ferts despite having algae issues.
oh man this should be good
 
#5 ·
If adding nitrate or phosphorous caused algae blooms, all of our tanks would look like bowls of pea soup.

There is such a minute amount of protein in algae (It's mostly water. When you hear claims that chlorella, etc. are high in protein, it's because it's something like 40% by dry weight.), that 1ppm can probably grow enough algae to coat everything in your tank.

You can try cutting the N if you think it will help. Just watch your plants and make sure they don't start "yellowing" out. It's possible the fish are producing enough nitrogen via ammonia to keep them fed.

The amount of nitrate you are dosing can never produce 100ppm nitrates unless the water isn't being changed or the NO3 is coming from some other source. You're only dosing about 20ppm each week.
 
#8 ·
If adding nitrate or phosphorous caused algae blooms, all of our tanks would look like bowls of pea soup.

There is such a minute amount of protein in algae (It's mostly water. When you hear claims that chlorella, etc. are high in protein, it's because it's something like 40% by dry weight.), that 1ppm can probably grow enough algae to coat everything in your tank.

You can try cutting the N if you think it will help. Just watch your plants and make sure they don't start "yellowing" out. It's possible the fish are producing enough nitrogen via ammonia to keep them fed.

The amount of nitrate you are dosing can never produce 100ppm nitrates unless the water isn't being changed or the NO3 is coming from some other source. You're only dosing about 20ppm each week.

I do a 50% water change weekly. The only other sources would be Aquasoil ( its been in this tank since January ), fish poop and fish food. I dont think I overfeed, all of the flake or pellet food is gone before I turn the filters back on--I do drop in a sinking wafer or two every night or every other night for the Corydoras and shrimp.
 
#9 ·
I suppose the sinking wafers could do it, but that's assuming that they aren't getting eaten, which is unlikely if you have shrimp and Cories.

I still suspect the test kit.

I don't have any experience with Aquasoil, but I've heard it will leach ammonia for several months. 7 Months seems like an awfully long time though.

Maybe it's a perfect storm of all the previously mentioned factors.

Honestly though, with 50% water changes every week, the fert input should never result in higher than around 40ppm, assuming the plants don't use any of it. If you graph out the function of the inputs with water changes, you get a line with diminishing returns, such that the resulting concentration will always stay just below 2x the weekly input.

Again, if you want to stop nitrate for a week and see if the levels decrease, I doubt that one week will hurt the plants much. There will still be some nitrogen compounds in the water, even if it's lower than optimal. I'd dose K via some other compound though. It's been my experience that potassium deficiency pinholes can appear fairly quickly under high light.

It's just hard for me to believe there's 100ppm of nitrate in a planted tank. Especially under such intense lighting. This is why I suspect the test kit.

BTW I tried adding pure KNO3 to a test sample, and it didn't register on my API test. I'm not sure what conclusion can be drawn from that, but it sure took me by surprize.
 
#10 ·
You aren't limiting NPK or micros or light. Suspect the tank needs more CO2 and if there is too much light you aren't going to be able to get enough into the tank without gassing the animals within. Cut back on the light period, shade the tank and use less nitrate.

EI is a guide, not an absolute. I cut back on my nitrate and add potassium instead and am going to up the potassium even more next time I fill the pill minder up. Why I still need the phosphorus I don't know but the tank is better off keeping that amount up there.
 
#13 ·
Really, the question about whether high NO3 and/or PO4 will cause algae has been answered many times by many people. As Sharkfood noted, we who use an EI fertilizing method would all have algae infested tanks if NO3 and PO4 caused algae problems. Continuing to debate the issue is non-productive.

I would never claim that it isn't possible to have a high light tank, even a 3T5HO lighted 29 gallon tank, with no algae problems. I would certainly argue that most people will have algae problems with that much light. All we try to do is point out ways to tilt the odds more in our favor.
 
#19 ·
I still think the poster who stated the CO2........was on the mark.

This bugger is a PITA.

You can rule out light, you can rule out nutrients.
These can be made independent and we can test and measure these with reasonable methods.

Not so with CO2.


What is a non limiting amount for CO2?
30ppm?

This too is an assumption, a guess.

Maybe it's 45ppm for S. belem, or 57ppm for Erios.
I do not know.

What is the toxicity level for fish and CO2?

How do we test CO2 for the entire light cycle and where do we measure in the tank?

Does CO2 ppm change over what time scale? light? Nutrients?

CO2 we can say is the main link and is the least stable of the parameters we add.

If we limit say PO4 strongly, this is predicted by Liebig's Law of the minimum, that adding more and more CO2 will not help. However, if you add lots of PO4, then some other nutrient, or CO2 will now become limiting. Liebig's Law also predicts this.

When folks limit say N or P, they often limit nutrients a little bit more than the CO2. So plants still grow...........and not much if any algae.
But not as fast as with the more nutrients and more CO2.
In otherwords, they have dependency on nutrients and CO2, whereas a reference tank does not have CO2 limitations no matter what the PO4, independence in the methods.

This is the error that the folks that believe the old tired myths and dogma make and then read it, accept it as truth and never question it, even when faced with a tank full of plants and nutrients, CO2 and no algae.

I guess you can believe in the tooth fairy, I prefer to believe in the Truth Fairy.
 
#16 ·
NO3 doesn't cause algae...for sure I can testify to that. I'm running about a constant 80ppm nitrates on my tank...not a spec of algae on my plants except spot and dust algae on the glass.
 
#25 ·
Bear with me for a moment:


Here's a video of the oldest goldfish ever (approximately 44 years old at the time of this recording): http://www.youtube.com/watch?v=SL3Fpt4tspc

It looks like he's living in a 5 gallon tank.

So is this evidence that a large fish that requires a lot of oxygen and produces a ton of waste will be better off in a tiny aquarium? No...... but luckily the owners haven't spent much time on aquarium forums writing articles and posts about the myths of overstocked tanks. Now, I'm not accusing you of anything whatsoever, but I think it's better to base your actions on common sense instead anomalies and forum posts.
 
#20 ·
Well, I think everyone doses too much as well.

My formula is to dose 1/.1/1 ppm of NO3/PO4/K per day and PPS Pro micro once a day. I change 20% water per week. CO2 is at 20ppm

I've been doing this for 3 years and waste 1/2 my plant growth every two weeks and can breed any kind of fish you can think of.

RTP
 
#23 ·
The object of EI dosing is to dose "too much" of everything, so nothing being dosed can ever be limiting the plants growth rates. If that is what you refer to, you are right.

As far as having 20 ppm of CO2 goes, it is nearly impossible to determine that you have 20 ppm and not 40 ppm or even 10 ppm, so I doubt that you are dosing 20 ppm. How are you measuring it?
 
#30 ·
Just to weigh in a little on this. Algae is usually the result of a combination of factors. One is daily thermocycling, the tank gets a little warmer during the day than at night during the summer. Lets face it, that's to be expected (but it also helps drive the proliferation of Cyanobacteria AKA algae).

Nutrients play a big role as well, most temperate lakes go through what is called spring bloom every year, this is due to the upwelling of nutrients that is driven by the temperature change. Realize too that this water coming from the bottom of the lake is also high in CO2, because despite decrease in respiration due to the extreme cold the aquatic life has still been slowly chipping away at the oxygen in this water all winter and releasing CO2. It is when this water that is loaded with nutrients and CO2 is heated up and exposed to light that this bloom occurs.

So you need to balance light, temperature, and nutrients to get rid of it. The high nitrates may not be a result of a true over fertilization. It may be the result of combining a fish load with fertilizers that are placing too much of an emphasis on nitrates. If your fish are providing the nitrates, then you need your ferts to emphasize phosphorous and the other trace elements the plants need. Be careful too, as I an sure you are aware many of these can be toxic in high levels.

Hope this helps.
 
#37 ·
#38 ·
@shane3fan: Looks like you won't get any good info out of this post and you'll just have to do some independent research. I suggest googling 'algae bloom' and 'eutrophication'. The general info provided by unbiased and credible sources will inevitably mention that an increase in nutrients, particularly nitrogen and phosphate, cause algae in freshwater ecosystems.

Now of course an aquarium is different from a natural ecosystem, but that doesn't make processes like the nitrogen cycle irrelevant either. So just use your head, test, observe, etc and the algae will eventually be under control.

Another thing I would recommend is making sure that you remove all the decaying organic matter from the tank. Adding a bag of Purigen also never hurts.
 
#42 ·
The scale of a lake and our aquariums is quite different. For one, we're only putting out about 10% the amount of LUX from our little lights compared to the force of the sun. In addition the amount of nutrients required to cause eutrification is really tiny...yes, really tiny. If you ever go to a lake bring your water test kit. You'll find that the nitrates, phosphates, and whatever else you take will be shockingly low. I'd be surprised if it even read on our kits! Eutrophication just can't be applied to the scale of a fish tank, no matter how hard you try.

You should just do what you want. In the end you'll get rid of algae but it depend on what cost: time most importantly. Lessening your light is the first step. Cranking up the CO2 is another good move.

Oh and where are your nitrates coming from? I'd try vacuuming the substrate if I were you. If I don't vacuum for awhile my nitrates get out of control.
 
#41 ·
HA--wow, this thread got way out of hand. My original post wasnt actually looking for an answer to my algae as much as it was looking for ideas of why the nitrate levels would be so high. The algae conversation was secondary and I do appreciate all of the thoughts and comments on that subject.

I plan to test the tank again before the next water change and see how it is after a week of no KNO3 dosing. I feel comfortable that the test was fairly accurate since my 'control' tank ( shrimp tank with no dosing and very light bio-load ) tested at zero nitrates with the same test at the same time using the same method as the tank that is in question with the 100ppm result. Still doesnt explain why that tank was sooo high though. I dont doubt that the 100ppm tank would be fine--I have a couple of gravid ottos, a berried red claw shrimp and the Harlequins are voracious eaters ( I call em litle pirhanas ) and a picture of health.

As a measure of algae fighting I removed one of the bulbs last night and raised the fixture a few inches above the water surface. I also added a wad of frogbit and dosed the tank with Excel. The tank doesnt 'look' as good to me without the intense light, but I will get used to it and be happy with it if the algae goes away and the plants have good growth. I still had pearling blyxa and stauro 049 after raising/reducing the light. I know pearling isnt the end all indication of happy plants, but it sure doesnt hurt.
 
#64 ·
My original post wasnt actually looking for an answer to my algae as much as it was looking for ideas of why the nitrate levels would be so high.
A few things came to mind as to why this might have happened. The first and most likely reason is an inaccurate test.

-residual chemicals from a previous test may have interfered with the results.
-the sample may not have been representative of the whole tank. Some parts of the tank are higher in organic compounds than others.

Also,

Reading test results can be difficult. Determining orange from red can be like determining green from yellow in our drop checkers. Since everyone's eyes percieve color differently its not the easiest thing in the world to do. Heck, one of my best friends sees green grass as the color brown! Try putting a white sheet of paper behind the results to make it a little easier.

Does alkalinity and other oxidants in the water affect these nitrate test results? I'm not sure but I thought I would propose the question.

All in all though, nitrates are a non-issue. I know you're not worried about this but to make you feel extra comfortable here's some interesting facts.

blue-gills have lived in 8,690ppm NO3 for short term exposures with no ill effects
catfish have lived in 90ppm NO3 over 140 days with no ill effects
Even the wimpiest of fish...salmon/trout and their fry, that need pristine waters to live in, can do well in waters up to 44ppm NO3
 
#50 ·
My stupid question that's related to the topic is, does it matter that the source of high nitrate and phosphate in our aquariums, at least one in which we add them, is predominantly inorganic while sources in a naturally occurring body of water the sources are more likely organic? Would higher levels of organic material lead to algae? That is making the assumption that high levels of the two contribute to algae in natural systems. Not that I'm claiming they do since I have no idea. I, by the way, am one of those who adds NO3 and PO4 with a pretty free hand to my tank with no algae issues to speak of.
 
#56 ·
I don't see any benefit to comparing aquariums to natural bodies of water. Even low levels of CO2 or nitrate or phosphate in a lake are not likely to bottom out due to the volumes involved. And even when they do, plants still have access to nutrients through the natural substrate they are rooted in. Some do use a nutrient rich substrate in aquariums, most don't. I believe, if one could keep nutrients in slight excess of demands it would be adequate to maintain a plant dominated aquarium, doing this in reality is almost impossible due to changing biomass and the limitation of our test kits. And in light of the fact that people keep algae free tanks when nutrients are far in excess of apparent demand, why bother? When most studies look at natural bodies of water, algae blooms, and eutrophication, they are almost invariable considering bodies of water in a steady state that are inundated with periodic pulses of nutrients. One should also consider the number of natural systems that are plant dominated with "high levels" of nutrients.
 
#88 ·
Firstly, a lot of people on this website use nutrient rich substrates like aquasoil and MTS. The original poster mentioned that he uses aquasoil in the tank with severe algae problems.

Secondly, why can't we apply the data from natural bodies of water to our aquariums? It's done all the time. For instance, many aquarists find that a balanced N:p ratio is necessary to prevent algae, which is both explained and supported by the 'Redfield Ratio'. Moreover, aquarists will tend to keep fish A in water warmer than 80F and fish B in water cooler than 80F due to temperatures found in fish A and fish B's native habitats. There must be thousands of similar examples of aquarists trying to tailor their tanks' parameters to those found in the native waters.
 
#63 ·
I think that horse is still breathing? So.....

Eutrophication in natural bodies of water becomes a problem when the resulting plant growth and algae bloom literally choke the water. In our tanks, an algae bloom is what natural bodies of water routinely have - the norm. We aren't satisfied with that norm since we want to be able to see the plants and fish, in their actual colors, not through a haze or covered with green stuff. Also, natural bodies of water get an order of magnitude more light than any of our planted tanks because the sun is really bright. And, normal plant growth in natural bodies of water is something we would consider unacceptable in our tanks (usually). All of that is to say that what causes eutrophication in natural bodies of water (eutrophication means an excessive amount of fertilizer in the water) is irrelevant to our algae problems. On the other hand my tanks probably compare very well with natural bodies of water eutrophication, as far as excess plant and algae growth is concerned.:hihi: But, I'm not typical.
 
#65 ·
I'm curious to see what your nitrate readings are over the next week or two. If they're going to stay high without the dosing, you could save a few bucks by holding back on the NO3. Most of us dose NO3 because it would bottom out otherwise, and use EI because it's easy.
 
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