I thought a UV sterilizer would take care of a bacteria bloom...? I know it'll knock out the single cell algae that causes green water. But yes, white cloudy water is a sign of a bacterial bloom.
As your shrimp and fish die, ammonia will be released into the water. Shrimp start to degrade quite rapidly in my experience. Your filter may handle the spike fast enough that your test kit won't detect it, but it's still happening. The frequent deaths could be a sign of ammonia spikes as well. I lost a lot of shrimp in a matter of weeks because I was getting small ammonia spikes as one would die and I didn't find it soon enough. I had some cloudy water during that time too. My tank was planted heavily enough that sometimes I never found their little shrimp bodies.
Yes but bulbs need replacement and often times over looked so I figured a quick swab of a suction cup could possibly identify the problem or at least eliminate it as a suspect. One thing I have learned in this hobby is things don't always work as they should and never rule anything out.
Bump: Also how much water are you changing weekly? and are you treating it and how?