brown algae and cloudy water...

Question
Hi there.  I hope you can help me.  I have a 120 gallon saltwater aquarium that has been up and running for about four months.  I am running standard t-12 48" flourescents (2-40 watt 20,000k, and 2-40 watt actinics), i plan on upgrading to a 260 watt cfl soon, i run these lights for 12 hours a day.  Everything was fine until about 2 months ago when the diatoms started.  It has covered everything and the water is extrememly cloudy.  The tank makes me sick to look at it and i want to slowly start working with corals when i get my new light.  (lower light corals that is)  All my water parameters are perfect.  I will say that i was using tap water for changes and top offs, but the past several weeks i been using wal mart drinking water since its treated by reverse osmosis.  I should also mention that my substrate is basic sand from home depot because i couldn't afford live sand.  before i go to reefing, im going to invest in a sweet clean up crew.  I have a yellow tang, clarkii clown, oscellaris clown, 2 blue damsels, a coral banded shrimp, and about 40-50 lbs of live rock.  the algae has killed all aiptasia and my condy.  Any advice would be tremendous, but there is nothing i can do until january.  Will everything be alright?

Answer
Hey Jason

Everything should fix itself, the diatoms sound like they were caused by the tapwater. good on using RO water, i would do double your regular water change schedule to get rid of all the tapwater sitting in the tank.

What kind of sand did you get from home depot? some sands will cause diatom growth, and that could be causing it. feel free to send me a follow up