snow like stuff.

[craig_will2513]

hi all iv been away for the weekend and while away i left my lights of.. i was only gone less than 24hrs so not really a problem.. but looking inside today it looks like its been snowing.. therre is a white powder like stuff covering everything. any thoughts as to what this may be

 

[hackteck]

got a picture of it? that will help people better help you

 

[ccCapt]

Sounds like calcium precipitation.
What is that Precipitate in My Reef Aquarium? by Randy Holmes-Farley - Reefkeeping.com