Originally Posted by squiggles1
you seem very knowledgable about planted tanks so i have a question you might have experience with. In our planted tank we have 2.6 wpg, diy co2 and quite a few fish. we are kinda recovering from a bit of an algea outburst (a bit of spot and maybe fuzz) our nitrates stay at about 20 usually and we try to keep our phosphates at 1-2. we just found a source of potassium that will do for now. we got a jar of potassium nitrate. Ok, that's just whats going on in our tank. The question is we have a cryptocoryne wendtii and some of the top leaves are turning a bit black. I'm sure this is a sign of something but i don't know what. we add ferts with trace elements like iron magnesium, etc. our lights are on for 9 hours a day (we have a timer). do u think maybe this is to long of a light period? our other plants seem to be doing ok, though one of our plants Alternanthera reineckii has turned completley red instead of red on bottom and green on top of leaves. That i read is from high light. Anyway, if you have any suggestion i'ld be grateful. we're trying to do all we can for our plants.
Well, to start at the beginning, how big is the tank? I usually don't recommend DIY CO2 for tanks over 30G-40G, as you really need lots of bottles to do the job, and you have a higher risk of fluctuating CO2 levels. But other than that, at 2.6w/g, you definitely need the CO2.
As for the blackening of the leaves, you have 2 possibilities. One is not enough nutrients at the roots. The other is too high Phosphates. High Phosphates cause the production of the Iron Phosphate which causes the leaves to turn Black or Brown and to die. In addition if there is an excess of Nitrates your tank will experience an Algae bloom. And there is also the possibility of Potassium deficiency causing it too, but there's not a lot of documentation on that. As for the Potassium, I wouldn't use the Potassium Nitrate. I prefer Potassium Sulfate. Potassium Nitrate does add Potassium, not to the recommended levels by itself. If you did, then you would be overdoing the Nitrates portion. But if it were me, I would start at the roots, and add root tabs. That may be all you need.
As for light time, you are fine. For your lighting, I would keep it between 8-10 hours. If longer, you may need to make dosing adjustments. I would keep it the same.
If you have any more questions, feel free to ask. I'll try to get them as soon as I can, but starting this Sunday, I'll be on my vacation and will be out of state til Thursday. So if any questions are asked, they may not get answered til I get back, as I'll have limited internet access while I'm gone. So if I don't respond, I'm not ignoring you, lol.