Is nitrate "sensitivity" overblown?

[SupersoNick95]

I have been trying to balance a high-tech planted setup. I have rummynose tetras, some corys and an Apistogramma agazzii in a 20 long. I have C02, a fluval 3.0, and an aquaclear 50 which provides excellent surface agitation and circulation. C02 levels are at a safe level running at about 1.5 bubbles per second. Drop checker is a dark green and has never gotten anywhere near yellow. I have UNS aquasoil under a coarse sand cap. This tank is about 7-8 months old but I admittedly neglected fertilizing for several months resulting in a lot of melt. 

I obviously wasn't dosing nearly enough ferts. My nitrates were always almost 0 and my plants were suffering. Lots of melt in "easy plants". I guess the c02 and light was pushing the pants to grow and the lack of nutrients led to melt. Ive slowly been trying to up my nitrates to somewhere around 40-80ppm, I have plenty of plants to absorb the nitrates. Plants are slowly starting to look a lot better and algae is dying off.

I have been increasing my doses of easy green slowly to account for the added light and c02. I perform a 5-gallon water change once a week. So far it has been difficult to get my nitrates past 40ppm.

The rummynose are looking great; very active schoolers and their heads are nice and red, indicating good health. However my apisto looks like it is about to die. No sign of heavy breathing but he is sticking to the bottom acting very lethargic and is barely swimming around. 

A lot of resources online suggest that apistos (and other cichlids from around the world) are extremely sensitive to nitrates. I suspect that this is a common boogeyman in our hobby but who knows? I doubt my apisto is dying due to excess nitrates. Could it just have been sick from the store? He has never looked very active even when I first brought him home. Again, my c02 levels look to be safe as all my other fish are healthy and active with no gasping or signs of stress.

I also care for lake tanganyikan cichlids that many consider "sensitive" and that cant be further from the truth, they are very very hardy once provided good stable pH. I monitor nitrates but not as obsessively as many online would want me to with africans. I try not to change pH in my planted aquarium in an effort to maintain a stable environment. 

 

 

Edited December 19, 2023 by SupersoNick95

[Fish Folk]

This is a touchy scenario to diagnose. I hope others weigh in, due to multiple factors here (e.g. high tech setup, Apistos, water chemistry details, etc.).

I agree with your assessment of plant situation. Certain plants break down when CO2 / nutrient / lighting levels are imbalanced. Your strategy seems fine for plant resuscitation.

Apistos can be tricky. I have never done exceptionally well with them long term. I've kept some Apostogramma cacatuoides and Apistogramma agassizii. If they can adapt to your water parameters while young and grow into that, they tend to do better. Most that I have bought at an LFS have brought home problems. Buying from breeders is preferable. Water parameters are serious considerations. Temperature + Nitrate + GH/KH can all be factors in how well they do. I'll tag @tolstoy21 and @anewbie for more developed experiences with the genus. If you can get Apistos to breed in your water, fry raised in your own water are typically much more likely to thrive there.

Given your post and awareness, I'll assume that you keep a good eye on pH. I have very soft water. Even passive CO2 (i.e. inverted 100 ml turbidity column with daily CO2 injections) proved enough to strip away my buffer, and lead to pH crash -- from ca. 7.4 to below 6.0. But I'd suspect major change like that would affect the Tetras to some degree as well. It may be that your agassizii has been fighting long-term ailment. 40 ppm Nitrate does not necessarily sound unmanageable to me. But shocks of up to 80 ppm might be a lot to swallow. You might consider taking a longer up-ramp, and not pushing the ferts too hard / too fast. 

[anewbie]

This is a topic which i have asked knowledgeable people about and take what is say with a grain of salt. 

 

First like many things this is a sliding scale - sort of like being exposed to 2nd hand smoke; it will affect some fishes more than others and at different rate - some species are more sensitive than others and individual fishes are more sensitive. But also it isn't cut and dry too much and you die instantly (like ammonia) rather it has a long term impact on health. So many folks would say xxx doesn't impact my fishes but what they really mean is the fish didn't die the next morning; not that the fish only lived 2 years instead of 4 years.

Last but least not all nitrate are equivalent. I never really understood this but there is an article somewhere that talk about nitrate from fish waste vs typical plant fertilizer. Of course fertilizer itself in any sort of noticeable quantity is adding pollutants to water.

 

Last but least most common domestic apisto (like many gbr) are a mess genetically. They have been bred for colour and have 'weak' genetics and frequently won't live as long as their wild counter parts. 

When a fish dies how do you determine why it died - did it die because you kept it at the wrong temp for too long a period (sort of the conversation with the fellow who keeps panda cory in a discus tank; he declares they do fine at 84 but only 4 of them live for 2 years and the other 8 die but he doesn't mention that).

Anyway my general understanding is that concentration of nitrate is not healthy for the fish but it is not like ammonia it just weakens the fish and makes the fish more likely to suffer from other issue (such as bloat); but there is no easy way to quantify the long term impact. I can't tell you if it reduces the life span by 10% or 50%. 

There have been some imperative data that suggest high nitrate contributes to hole in the head disease so there is that data point.

Remember for many fishes the best thing you can do is frequently change the water to keep it pure so that should be a hint that additives are generally speaking having a negative impact.

 

[Biotope Biologist]

I think the topic has pretty well covered, but I just wanted to tackle the nitrates reading and your plants.

 

With mature plants and tons of plant growth you should have a very hard time reading nitrates in your water. Unless you have a real time monitor that conducts readings every 10 minutes it will appear to you that your nitrates are always at 0. When in fact they are not. So if you were to somehow dump a bunch of nitrate fertilizer in your water to get it to 40-80 ppm you would likely injure/kill your fish and shock your bacteria population. Id advise if you are seeing melt you can add more fertilizer using the somewhat accurate leaf chart. But chances are they are missing some sort of micro nutrient and not nitrate. 
 

Eventually plants will get to the point where they starve algae out of the water for competition over the same nutrients. Only mature algae will survive. 
 

[Mmiller2001]

On 12/18/2023 at 8:57 PM, SupersoNick95 said:

Drop checker is a dark green and has never gotten anywhere near yellow

The drop checker should be lime green, dark green indicates suboptimal CO2 levels.

 

On 12/18/2023 at 8:57 PM, SupersoNick95 said:

Ive slowly been trying to up my nitrates to somewhere around 40-80ppm

There's no reason to be this high. 30ppm of NO3 is more than enough for plants.

 

I have had decent luck with Apisto's, and if this was me, I would do a round of Paracleanse and a round of antibiotics (fed directly) just to eliminate those possibilities.

[tolstoy21]

@Fish Folk Unfortunately, I don't really have any experience or knowledge to share on the topic of apistogramma and nitrates.

I honestly don't measure my tanks for nitrates but I also change so much water my nitrates are probably always close to zero.