First inspect your lighting system to see if you have a T5HO or T5NO. For low-light setups, you'll want T5NO. You can also buy cheap T5NO fixtures and bulbs at Home Depot. I forget what spectrum and K rating you need for a low-light tank but I think you can find that info somewhere in this forum. Generally, you'll want something of a .5 watts to gallons ratio.
You'll have a tough time keeping plants with just black sand even though the root tablets will help. You've pretty much limited yourself to anubias and other plants that don't need richer substrate.
A lot of things can cause algae, poor water quality, old bulbs, lack of water movement, long photoperiods, extended exposure to natural light.
To fight the algae, I would recommend more frequent water changes then look at the lighting setup if the algae doesn't improve.
Last edited by The_Finglonger; 07-22-2011 at 09:08 PM..