Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
One way to reduce the light is to lift up the fixture.
Keep things in balance.
First: N and P
Fish food should be enough when the tank is running as a low tech tank. If the NO3 test keeps hitting zero, then you need to dose these, and it is not a low tech tank.
K: Even low tech probably needs some K.
Iron: My low tech tanks needed it.
All other micros: Fish food might supply, a little extra is not a problem. Follow the N and P idea: If you need to dose 'cause the plants keep using up all the N, then they are highly likely using all the micros.
Carbon: I would dose Excel, but keep it as stable as you can. Dose daily, every other day maybe. I would not spread it out to weekly or even twice weekly. If you are not dosing N or P, then a low dose of Excel will probably be fine.
As my tanks moved from high stocking level, low tech (low light, no carbon) to sort of medium (double the light, but also a few less fish) they started needing more nutrients.
Low tech: K, Fe, low dose of C.
Medium (sort of): N, P, K, micros (including Fe), C
To minimize the time you spend caring for the tank you might think about:
Fertilizer tablets under the substrate.
Auto dosing ferts, including Excel.
Go with a dirt substrate, and some of the organic matter breaking down supplies carbon and the other nutrients the plants need.