I have dual daylight bulbs on my planted tank. They are fine for a planted tank and give nice color to both the plants and fish.
You have a total of 3.5 watts per gallon over your tank. You are going to get algae at this light level if you're not using CO2
. Also, 12 hours per day of light is a lot. Set your timer for between 8 and 10 hours of light. I run my lights for about 9 hours.
Is the tank only one month old? Brown algae, called diatoms, is common in new setups.
You can keep the bulbs and the light level at this intensity if you use CO2
(pressurized is best at this light level and tank size) and fertilize properly. If the nutrient level drops (specifically nitates) algae will appear.