cloudy water

ok so heres my problem, during the day my tank is crystal clear, but at night it clouds up and takes about 3hrs to clear up after the lights go on
.... i have a wet/dry filter with bio ball , carbon, filter floss bio glass ,, and the tank has been up for about 3 months with no problems besides when this started the other day ...... its a 40br with 2 clowns,tinytiny blue cromis, wrass, and my wife got a yellow tang which i know its to much for the tank but the problem is she got it at petco $45as a surprise and i cant return it, 1 day later (they said i cant donate it tho lol). but i have had it for about two weeks now ,, all my parameters are good ph 8.2-8.4 amm 0 nitrite 0 nitrate is a little high 20ppm phos 0 calc 380 dkh 9 kh 161


any help would be good on ideas

 

Try pumping up the O2, either by aiming the power heads towards the surface or adding more flow.

Are any of your fish like the clown stirring the sand to make a depression?

 

What kind of wrasse is it?

 

its Diadema Dottyback sorry not a wrasse





and yes the clowns are always stirring up the sand but not getting the whole tank cloudy ... its weird my tank is crystal clear today , hopefully it stays i added some more live rock yesterday