Question
I have a 29-gallon planted tank with mollies, mystery snails, and several live plants.
One of my plants has been showing signs of yellowing leaves:
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I use Seachem's Potassium, Nitrogen, Phosphate, and Flourish liquid fertilizers in the specified doses twice a week or so. I also use Seachem Flourish root tabs, and recently added more of those. However, it doesn't appear to be helping. I don't use any kind of carbon dioxide supplementation.
I use white LED lights. The aquarium gets indirect sunlight. Right now nitrates are higher than usual at around 25 mg/L (I'm working on reducing that, they're usually quite low; in the past they've sometimes been pretty close to zero) with zero nitrites or ammonia. Total Hardness is on the high end, somewhere between 75 - 150 mg/L.
Does anyone have any suggestions of what the problem may be, or of other things I could try to help the situation?
Answer
From my POV, you are doing it the wrong way. One of the best fertilizers for aquarium plants is a cycled aquarium. The fish (and other "animals" you may have) make a lot of Nx substances, which are just perfect for the plants.
The most important thing to do is to get rid of all the algae. Even if the fish and the snails seem to eat it, they (the algae) create all sorts of mysterious problems there - one of them being lowering the level of oxygen in the water.
So please find some solutions on how to get rid of all the algae, use them (the solutions), stop fertilizing, and then see how things evolve. This path might require you to actually start everything over - which should not be excessively difficult, I do not see a lot of complicated details (e.g., landscapes) in your tank.
In my small tank, too much light allowed the plants to grow so much and so fast, that they killed almost all my fish and snails very quickly - with no fertilizer added at all. Now I keep things under control with a dimmer for the lights.
A small comment: I used some liquid fertilizer at the beginning, when there was pretty much nothing in the aquarium to resemble nutrients for plants. But that time was short, the fish created very quickly everything needed by the plants in terms of food.
Answered By - virolino
