I agree with BToast on everything. Syphon the sand daily, maybe cut back on light cycle, cut back on feeding, maybe get some turbo snails to help clean the hair algae, and get some more flow going.
What you are going through is definately typical to what most people setting up their first SW tank deal with. This is usually the make or break point for most people though. Now you have to really get involved with maintanence/testing or else the algae will consume everything and crash the tank. Either people start to do more and get things under control, or they throw in the towel and this very common stage in a tanks development.
Here are some helpful items I have found and use from years of experience:
1. Phophate remover, aka GFO, is a must have item IMO. Personally I swear by RowaPhos and only use that in a reactor, but it is about 2x as much as Phosban. In your case I would suspect you have high silicates as well due to using tap water in the beginning.
2. Chemi-Pure + Purigen, 2 great products to help remove bad stuff in the tank.
3. Red Slime Remover - Great product to remove Cyano, follow the instructions and do back to back treatments to really remove cyano. Everyone deals with cyano, no matter how long the tank is setup. One or 2 days of higher than normal heat will bring out cyano fast in anyones tank. This won't get rid of it if you don't address the cause of it though, but it is a good product to get the tank back into a more manageble state so you can find and solve the source of the problem, either heat, overfeeding, lack of flow are the culprits.
4. Phosguard - Great product to remove phosphates and silicates in a hurry. Media only last a few days though, but another great product to get your parameters back down to a managable state while you find the source and solution to phosphate/silicate issues.
High Phosphates = lots of hair algae/diatom (brown algae in sand)/cyano - caused by overfeeding/bad water
High Silicates = usually caused by bad water, either tap, or bad membranes on RO filters
High Nitrates = Not enough bacteria in the tank to balance the bio-load + not enough water changes. You can have less live rock in a tank if your willing to do greater water changes to keep nitrates low.
Low Flow = cyano and hair algae outbreaks in spots