Originally Posted by Toad
Well I want to keep it low tech, I may be able to find another light strip... will start adding flourish twice a week and see about the excel. The tank has a bunch of guppies, a bn and a keyhole so I guess I assumed the ferts were covered lol.
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This seems like severe nutrient deficiency of some sort. As far as macros, I'm guessing you can get away without adding nitrogen or phosphorous (depends on fish load and amount of plants/growth rate), especially since growth will be slow with only a 15W bulb. most tanks will need to be supplemented with potassium at some point. API Leaf Zone is widely available and contains both potassium and iron. Also, if the GH
of your source water is low you may need to add a GH
booster to provide a source of calcium and/or magnesium for the plants.
Your lighting is definitely going to be on the weak side, but if you've had success with your lighting before this and don't want to change anything, you might just need to go ahead and replace your bulb. There's a chance it is no longer putting out quite enough light. While you're at it, wipe any deposits off the foil reflector, or even better just replace it with new foil.