What is the nitrate tolerance for discus?

[Johanna]

Interesting thread...I've found that the more often I change water, the better even my plants grow. Nitrates are around 10 ppm with my current schedule of 30-40% water change about every 3 days. I feed 2-4 times a day depending... Almost no algae these days and much healthier plants than I had in my old tanks (before discus) with 50% water changes whenever I remembered.... every couple of weeks or so, NO3 being around 25 ppm. I have some plant species that are supposedly not very well suited for discus tanks that are doing ok in mine. The only problem is my plecos keep munching on the bigger leaves.

My theory is that when there are a lot of nutrients in the water there's easily something off-balance and algae benefit from it causing problems for the plants and plants consume less, making it a cycle. But when nutrients are scarce, plants use everything and grow to the maximum that the lowest level nutrient allows.

[brewmaster15]

In the wilds where aquatic plants grow the levels of nitrates in non polluted surface waters are generally less than 1 mg/liter... just saying
https://archive.epa.gov/water/archiv...%2030%20mg%2FL.

[For100]

I am not surprised…. Plant consumption of nitrates, phosphates or any other nutrient does not increase if concentration increases. It is all about the limiting factor, it could be one element or CO2 or amount of light or even the amount of plant mass.

Takashi Amano, the greatest aquascaper in history, always advocated for minimalistic approach in his books. Minimal fertilization, but keeping a close eye on the limiting factor by monitoring concentration of macro elements (Nitrogen, Phosphorus and Potassium). It is all about stability rather than concentration, thus it does NOT work in your favor to dump a large amount of nutrients expecting fish and plants will be OK with it.

BTW, he also pushed for regular water changes to RESET the balance of nutrient in his tanks.