Water has gone milky.

I just got home from work to find my tank water has gone all milky, I can't see the back of the tank. Tank has been running for years with the water always clear. It appears to have happened in the last few hours. The fish are still alive but I don't like the look of things. Any ideas on what could have happened?

 

bacteria bloom? I'd do a water change.

 

What's in the tank (livestock, including corals, snails, etc.).
What are the parameters?

 

Thanks for the reply. Any idea on what causes a bacteria bloom?

 

Too much food or something dead?

 

a number of things really...but usually an over-feeding...also check your params...ammonia will also cause cloudy water...either way i'd be sure to get a WC done as quickly as possible

 

Thank you for all the replies. I haven't had time to check all the parameters just now but they were all fine a few days ago, I check them all the time and had my LFS do a double check them last week.
I bought a small wrasse (can't remember which type) a few weeks ago and I haven't seen him for about 2 weeks so assume it died, it was about 2 inches long, so not a big fish. I haven't changed my feeding amounts.
Unfortunately I have to rush back to work now but I will do a water change when I get back in about 2 hours. Thank you all for your input.

 

If you can not see the back of the tank, I suggest you at least add some more oxygen and some new carbon. Personally I would not leave the tank for 2 hours without an intervention a bacterial bloom can wipe out your tank in 2 hours.

Perhaps someone can assist you, good luck.

 

Sounds like a bloom to me. I would do a water change and also add carbon. you should be fine unless you house SPS if so it may burn them. Wc and carbon is your friend right now

 

Did a water change and added carbon about an hour ago. Parameters are pretty much the same as a few days ago.
Nitrite 0
Ammonia 0
Nitrate 0
Phosphate 0
PH 8.3
Carbonate Hardness 250 PPM
Salinity 1.025.
Temperature 27 degrees celsius (around 80 F ) it's summer here.

Water is rapidly becoming clearer, fish and corals showing no sign of stress.
I lost both my father and my dog last week and for I while there I thought I would lose all fish and corals as well. Bad things usually happen in 3's.
Once again thank you all who helped.