film
 

My 90 gal new tank as a thin film on the top of the water. any idea what it is?
Is it safe?
should I try and get rid of it?
How do I get rid of it if I should?

Roger

90gal fish tank
sump with large sock filter.
UV light.
two 150W metal halides
two 90W power compacts
water nitrates 40ppm
amonia 0
nitrites 0
temp 81

Do you have any powerheads.

yes I have the pump from the sump moving water in 2 directions and I have my pump for my UV moving water in the main tank and I have 2 additional power heads.

Its probaly not enough to move the surface of the water. The film is the particles in the water floating to the top. You need to have a PH break th surface of the water so the film wont accure.

can this happen because the power heads are set to deep in the water? or is it simply about water movement? I have the power heads set lower in the tank.

Thanks Roger

In mine I have 4 powerheads 2 at the top to break up the surface and 2 on the bottom to give movement in the bottom

Definitely need much more surface agitation. The film, bio organic materials other wise known as algae food, is preventing proper gas exchange. This could cause all kinds of problems from low oxygen which is bad for living creatures to high CO2 which creates carbonic acid and will cause your PH to fall out quickly. You mention having 2 powerheads in a 75g. What size are they? I only have 2 as well in my 75g except they are each rated at 1,600 gph, Tunze turbelle stream makers. Proper flow is extremely important.