RO water stands for Reverse Osmosis, which is a purifying process. Tough to tell how pure the ocean water is that you use but it doesn't hit me as the likely cause.
Your food however does, flake food is very well known for being high in phosphates and if you are not exporting enough it could be building up quickly and fueling the nuisance algae. Algae on your sandbed can also easily be too little of water flow causing dead spots.
If you wish to continue with the flake, I would analyze the following:
Export--Do you use a skimmer, if so, what kind? If not, how often do you do water changes...do you siphon the rock or just remove and replace water?
Water Flow--What kind of system do you have in regards to filtration and water movement (filters, powerheads, a sump, etc.).
Stocking--What size tank do you have, what livestock do you keep?
Water Parameters--ammonia, nitrite, nitrate levels as well as salinity/specific gravity, alkalinity, and calcium if possible. Sometimes just a few of these out of whack can help nuisance algae proliferate.
These answers will help get you going, and new ones will come out of them as well. One thing I would not do is really cut down on your lighting (a few hours down to 12 may be fine though, I timer helps make things accurate and easy each day). Yes, it may reduce the algae, but you are also removing the light source needed by more desirable algaes (most notably coralline) that can outcompete nuisance varieties. It also does nothing to solve the problem, if you return to a normal light period the algae will simply come back because the source of the problem has not been reduced or removed.
. when i top off, i use fresh water from my tap. i bet thats where the phosphates are coming from... i have a 5 gal container that i let sit out at lest overnight, to get the chlorine to evaporate, and i just top of as needed. when i do water changes, i go into the LS, and clean as much as i can. the algea is stuck to the LS, it doesnt come of easily at all. i cant get a clear shot for a pic, sorry. my light is jsut what the lfs told me to get, some 50/50 something or other, im going to get a new one for when i start corals, but my flow is very strong, sometimes, my fish catch the current, lol. should i move my poweheads closer to the bottom?? ill get a phosphate test and test.......if it is high, how do i lower it???
