It appears that I have some diatoms or other brownish red algae starting to form on my sand bed, so thats good.
As long as its not Deep thick red you are fine. Brown slime Diatom algae is part of having a new tank, its not ony unavoidable, its desirable. The only way to avoid it would have been if you literally took the sand, rock, and water out of another tank and just transported it in with yours. Even if you used RO/DI water for the intitial fill up (which i have never done as it would take forever for me to make that much water at once), you would probably STILL get that. My tank has been cycling two weeks now and it is JUST now getting that on the rocks (i assume because thats the only place it can grow with the clyclone of water circulation i currently having going on in there presently...lol).
Also dont kill youself watching the tank and tinkereing with it. Other than sitting around buying equipment (like lights, pumps, wave makers, RO/DI units or what ever other stuff you need/can afford)....literally leave it alone. A watched tank never cycles.
I leave my lights on 24hrs the first week and bump the temp up to around 82 degrees and run cheap low k rated rated lights over the tank for the first month, along with running a cannister filter (all help promote bacteria and algae) and wont even BOTHER testing the water for a month. After a month, ill dial back the temp, get rid of the cheap floursents, but ill run the cannister for a full 3-6 months before removing the denitrfying biomass (read nitrate producers) and only running it with a prefilter screen and the occassional carbon. (just my .2 cents). After that you have to make sure you wash off the prefilter at least once a month and replace it about once a year.
If i were home all the time i would set up an overflow and a sump but im gone 4 days a week and its just not safe to run a sump of any kind on an undsupervised tank (its challenging enough to keep a skimmer dialed in on a cycle that will last 4 days before needing empting)...
Really limits what i can accomplish as a reefer but i digress......