Green cloudy water - HELP

Actually it is algae. Even if live rock is cured you're going to have some die-off. You may have quite a nutrient build up and that just tipped the scale for a bloom. I'd run the canister empty. That'll help in preventing waste from accumulating which just adds to the problem. Also, how often are you doing water changes and feedings? You should do a couple of water changes over the next week and a half or so and maybe feed a bit less. Again, that'll cut down the nutrient level. And one final question how often do you have the light on? If there isn't anything in there that needs the light, don't bother turning it on unless you're looking at it. The fish don't need it and it only adds to the problem.

Yep, you have algae. Is the tank in a position where it receives direct sunlight at any time during the day? That may be your culprit. Aside from sunlight, the causes are nutrient accumulation (which Voodoo explained) and phosphate accumulation. Phosphates typically occur in relatively high levels in tap water. If you are using tap water for your water changes, then it may be contributing the the algae growth. Try using reverse osmosis water, or try a personal favorite trick of mine. Buy a PUR tap filter, and just use that. It is cheap, and seems to remove enough phosphate from city water to not cause aglae problems.

How much live rock do you have in your tank? I would not remove the filter media from your canister until you have at least 1lb per gallon of live rock. If you remove the filter media now, you will get a large ammonia spike. Wait until your you have the full amount of live rock and then begin to take the filter media out of your canister filter.

Brian

Do you have anything in there that needs the light (ie, corals, caulerpa, anemone)? The macro algaes on the LR will suffer from no lights, and you should verify that you do not have high phosphates or nutrients before just turning off the lights. Right now, the free floating algaes are thriving, and if high nutrients are the culprit, then turning off the lights will result in a spike of ammonia/nitrates, since the algae will die, plus the amount they are eating will still be in the system. 12 hours of light is not enough, by itself, to cause an algae bloom.

Phosphate levels accumulate in an aquarium over time, regardless of how much is in the tap water. Once it reaches a certain level, the conditions are right for a bloom, provided there are sufficient levels of dissolved organics in the water for the algae to sustain itself. It appears that you met those conditions. Using RO water or running it through the PUR filter are simply ways of REDUCING the amount of phosphates in the tank. To reduce the amount of dissolved organics in the water, continue doing your water changes with the filtered or RO water.

Is your skimmer producing a good amount of foam and scum? You should have to clean it every 3 or 4 days. Skimmers are a good way reduce dissolved organic buildup, but only if they are working properly. If you aren't getting good foam, check the venturi and make sure you are getting tiny bubbles, the smaller the better.

Once the algae have exhausted their food source, they will die off. This may take a while, and in the meantime,you may just have to deal with discolored water. It is part of the normal cycling of the tank, though. After my tank had been up a month, I had an explosion of green and brown algae. It wasn't pretty. I brought in a small army of scarlett hermit crabs and turbo snails to combat the brown algae, and some blue legged hermits to get the green algae. I'm told that mithrax crabs work wonders on green algae as well, though I don't know about their effectiveness against free floating algae...