Slimy stuff on top of water in return section of sump

[neurosis05]

I have a 90 gal DT and about a 30 gal Berlin style basement sump. In the return chamber I've been noticing a white slimy film. The tank was set up as a 75 gal for years in a different city and I moved it to a 90 gal and added the sump back in November. I know the film may be from over feeding (my fiancé usually feeds them and I recently found out she has been giving them 2X what I told her to). I have two clowns, a yellow tang and a Majestic angel. She was giving them a whole cube of mices shrimp as well as a 1" x 2" marine algae daily. Nitrates are high now but thats all

At any rate I can't seem to get this stuff to disappear. I added a power head to the return section but the film remains. I find it odd that it is only in the return section of the sump.

Why don't I see it in the DT or the filter section of the sump? Is it because there is that much more water movement in those areas? Could the return section be too big? I've seen some people cut notches in the baffles, is this recommended? I do see protein build up in the baffle section.

Also my angel has been picking at my mushroom coral. Do mushrooms give off a slimy film for protection? Or is this from over feeding? Or could it be new tank syndrome even though its established?

I know there are a lot of questions here, any advise would be appreciated, thanks.

[Spyderturbo007]

I ran into this a good bit when I was dosing Vinegar and still get it to some extent now that I have stopped. Mine also only appeared in the return section of my sump, which I'm assuming is because the flow is so low and there is no surface agitation. I was told it was a bacterial bloom and nothing to worry about. I just net mine out during water changes.

[neurosis05]

Yeah I siphon out what I can during weekly water changes. I find it strange though that I have a power head in there and its still not enough water movement to stop it from forming

[Kyle918]

Yeah I siphon out what I can during weekly water changes. I find it strange though that I have a power head in there and its still not enough water movement to stop it from forming

Is the powerhead positioned upward to break the surface of the water?

[Fizz71]

Is the powerhead positioned upward to break the surface of the water?

+1 You need to ripple the surface. I get it in my DT in a corner 8ft from the nearest powerhead if I don't ripple the surface enough.

[neurosis05]

Is the powerhead positioned upward to break the surface of the water?

yep it was aimed up but wasn't doing much so I put it on the ground to aim it straight up so now it really causes surface movement.