High nitrate content from lack of water changes can cause small brown spots, developing into holes and yellowing leaves on plants??? Is that the same as overdose of Nitrate fert? or it's something different?
I've maintained 75 ppm for long time frames, as well as some spikes to 150ppm +, Richard Sexton had done some up to 200ppm for several weeks, no issues for fish or plants. Shrimps died at 160ppm for me(LD 50 for a 3 day exposure), not for Richard.
He thought the 200ppm was 20ppm :hihi:
Do a water change and focus on other nutrients/light/CO2 etc.
There is no need for more than 30ppm of NO3 for any plant species.
Great! Glad to hear that higher nitrate content would not burn leaves with brown spots. I have some brown spots (dime size) on matured swords leaves. They are in a low tech tank with 2wpg, no CO2. Could that be a potassium deficiency?