Cloudy water (only during the day!)

[stoneage]

My marine tank has been going 3 months and all of a sudden the water is a cloudy (milky white) the strange thing is that in the morning its clear and it gets more and more cloudy during the day only to become clear again in the evening. All water params appear ok, Nitrite 0, Amonia 0, Nitrate 5.0, PH 8.3, SG 1023, Temp 25.5.
Tank size 48 inch, stock : blue yellow tailed damsel, bananna wrasse, orchid dottyback, rusty angel, green chromis, flame angel, fire shrimp, boxer shrimp, 6 red hermit crabs .
Filtration is a Juwel internal 1000lph and an external ECCO 600 lph there is also a 400 lph powerhead.
No protien skimmer.

 

[FL Knifemaker]

Every once in a while, my liverock will expell a bunch of, Uhm..........for the lack of a better word, POOP! It will briefly cloud the tank and then it's back to normal. Right now I'm running a pretty good size mechanical filter with a pretty high GPH rate so it clears the tank rather quickly.

 

[stoneage]

It's not live rock because I havent got any, I suspect its bacterial, the odd thing seems to be the timing. Its not just visible because of the extra light during the day,if you close the curtains to cut out the day light. its still appears cloudy. Also its winter here in Britain and even when its not cloudy, you can hardly call it bright outside.