Hello,
This is another illusion that folks misinterpret. There are no measurable long term negative effects of NO3 levels at 50ppm. NO3 production is the method in which natural systems detoxify. NO3 is actually the termination of a toxic sequence. The real toxicity in a discus tank, or in any tank, is the NH3 that it starts out as and the NO2 that it gets oxidized to. Those are the killers in the tank. Furthermore, the oxidation sequence NH3->NO2->NO3 requires oxygen, so this so-called nitrification cycle steals oxygen from the water.
The long term and short term damage to fauna in a tank is a direct result of the high toxicity of NH3 and NO2, plus the hypoxia caused by the bacteria's theft of oxygen from the water column in order to maintain this cycle. NO3 is merely the smoking gun.
Discus keepers force feed their fish with massive amounts of high protein foods. Protein is high in nitrogen. Uneaten foods, as well as the high urine and fecal production from the fish generate huge amounts of NH3. This is where the cycle starts. Large water changes are required to rid the tank of the buildup of the toxic substances. So they think they are getting rid of nasty nitrates but in actuality, they are ridding the tank of organic waste products which generate the nitrate.
When you add inorganic NO3 to the water, since NO3 is the end product of the nitrogen cycle, there is no further breakdown. There is no NH3 or NO2 production. Equally important, there is no oxygen theft from the water column. That is why 50ppm NO3 is completely safe, whether short term or long term. A CO2 injected tank suffers the same fate as those discus tanks. High production of organic waste from the plants themselves enlarges the NH3 production rates and so water changes in a CO2 tank is imperative, both for the sake of the fish as well as the plants.
The kits are not accurate. More importantly, they are not consistent. I will bet the farm that you do not have 30ppm NO3. The real number can be anything, and will probably be closer to 3 than to 30 if you have plants in the tank. You have never known what the nitrate level in your tank is. You have only been hypnotized by test kit vendors who have told you, without ever showing any evidence, that their kits return valid data. Calibrate your kit using distilled/RO water + known amounts of KNO3/KH2PO4 and reveal the illusion.
This is why people have all sorts of algae problems in their planted tank, because they depend
on the kits to tell them what's in the water. The kit returns high readings like 20ppm or 30ppm when the number can be ten times lower. The plants starve, causing algal blooms and they never even consider adding NO3/PO4 because someone told them these are evil chemicals. So people buy all kinds of products EXCEPT the products that are the healthiest for the tank. NO3 and PO4 additions are crucial to the success of the plants in a CO2 tank and their addition results in better plant health as well as better oxygen production in the tank, which is vital for the health of your fish. I don't experience any long term or short term effects of high NO3/PO4. People only blame NO3 for their problems, again, without any evidence, simply because "some discus keepers" are afraid of it.
Cheers,
Cheers,
