I agree. Water changes, water changes, water changes. I'd do about 10% or so daily. Pull as much and scrub as much as possible.
I don't know how you're getting your water (RO, tap, etc..)but when mixing, try to allow at least 24 hours to aerate. You don't want any spikes especially if you don't currently have a way to test your water. Do you have a hydrometer or refractometer? If not, I have a couple of hydrometers laying around. I use a refractometer but a hydrometer is better than nothing. If you don't have one, just pm me your address and I'll send you one you can have.
I highly recommend asterias just from personal experience.
What's in the tank??? Fish, corals, etc...
Depending on what you have, you can get away with cutting your lights down assuming you don't have anything that depends highly on it. Every little bit will help.
If I were you, I'd take your water to a LFS or even petco, petsmart and have it tested, write them down, and post them on here. The others on this site know a LOT more than me but having your water parameters and what's in the tank will help them troubleshoot you.
I personally would not get a fish that eats algae like a tang or anything until you know what your water parameters are. Snails are a much cheaper investment if for any reason you have any Nitrites, Ammonia, Salinity off, etc...
Good luck!