How long should I leave my lights on?

[tedisabum]

I have a 20 gallon Malawi tank and I have two choices. I can turn the tank lights on before I go to work at 7:30AM and leave them on until 8:30 PM, or I can turn them on when my wife gets home at 4:00PM and turn them off at 8:30. I definitely notice a decent amount of algae build up in my tank that takes me 2 hours each week to clean when I do my water change. I take all the decorations out and brush them off, clean the glass, and then gravel vac. I notice that if I turn my lights on at 4:00PM instead of 7:30 AM, i get almost no algae build up. This would be ideal, but I'm not sure if it's bad for my fish. It's like 13 hours of light each day, or 4.5 hours of light each day. Does anyone know what the best choice is and why?

PS. I have plans of upgrading my tank size soon.

 

[bracey87]

Not a expert but can't you get a timer and set it to turn the lights out in 8 hours save you alot of agro with the algae

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[mikem691]

4 or 5 hours will be fine. I only run mine 6 a day and its planted

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