Jul 11, Aquarium in a location with direct sunlight. Feed Less – The majority of owners overfeed their fish, which increases the phosphate levels in. I want to make a planted tank on natural sunlight. My idea is to have a any fish in the tank will keep it free of mosquito larvae. Floating plants. I get sunlight in my tank room through windows which face north and west. Any ideas how this will affect my tanks? What do I need to look for?. Aquarium Algae Tips, Causes of Algae in Greenhouse Sunlight Tanks Feb 2, I was wondering if direct sunlight on the aquarium was good or bad. I have a 55G FW with two 32W T8 Daylight bulbs, about 12 hours day cycle. Mar 25, No it won't. Direct sunlight hits about 1/3 of my g and the fish actually seem to like to spend time in that area for the time the sun is in the. Apr 1, Sunlight can overheat the water temperature in an aquarium very fast. Also, the temperature will also drop rapidly as soon as the fish tank is no.