UV sterilizer

[Mappelbaum37]

Hey- Ive got a 75 gallon tank with 5 fish and a couple corals. For some reason a type of dirt substance keeps coming to the surface of my tank and i dont know if its algae or waste. Would a UV sterilizer be ok to add to the tank? I wasnt sure because I was told that it kills the bad bacteria but also good bacteria but keeps the tank water crystal clear

[Entropy]

A UV kills just about everything that goes through it (good or bad). It will help clear your water, but what I think you have is not enough flow at the surface. Is this stuff all across the tank or just on one side or in a corner? If you don't have enough flow at the surface your water will stagnate and yucky stuff will accumulate. You might want to try adding a power head. Basically you need to get this stuff to your skimmer so it can remove it.

[Mappelbaum37]

I have 2 koralia power heads breaking the surface with a fluval 405 filter and prizm protein skimmer- I was considering getting a surface skimmer

[Mappelbaum37]

I have 2 koralia power heads breaking the surface with a fluval 405 filter and prizm protein skimmer- I was considering getting a surface skimmer

[Mappelbaum37]

I have 2 koralia power heads breaking the surface with a fluval 405 filter and prizm protein skimmer- I was considering getting a surface skimmer

[Roger928]

The UV won't have any affect on the surface film you've descibed. These are DOC (Disolved Organic Compounds) which need to be physically removed (usually through a skimmer) or some other bio-mechanical process. If you're satisfied with the output of the Prizm, think about additional (strong) surface agitation. The surface skimmer will help some. Also, look into reducing the amount of feeding. Frequent changes of carbon or Chem Pure may also help.

IMHO, UVs have very little to offer in a properly maintained system.