Snails and sea hare at the top of tank?

[SATAN FISH]

Recently, my nassarius snail and new Sea Hare are sitting at the top of the water level. I don't know why. My snail has been sitting at the top of the tank for about two weeks now. The sea hare I just put in the tank yesterday, he did not seems to be doing good until just today. He was just kind of floating around not really sticking to much. I acclimated him by dripping tank water into his water for about 2 hours.

The only thing I have changed recently is... I quit dosing vodka about a week ago. Other than that, I have been doing bi weekly 15% water changes with reef crystals (thats all I ever use). Since I quite dosing vodka, I noticed a film on the surface of the water. looks like a very find dust that sits right at the surface.

Anyways, what is it that would cause snails to sit at the water surface like that and not come down? Everything else in the tank is doing fine, corals, coraline algae, crabs, shrimp, fish... Just the snails/sea hare.

 

[Runfrumu]

Maybe theres not enough algae in the tank for them to eat and they are staying along the water line eating the algae that forms there?

 

[Koshmar]

Sounds like a dissolved oxygen problem. Do you have proper water surface agitation? You should never have a film on the surface of your water.

 

[SATAN FISH]

Sounds like a dissolved oxygen problem. Do you have proper water surface agitation? You should never have a film on the surface of your water.

Hmm, I guess that could be. My return from my refugium is now pointed down in the tank instead of at the surface like it used to be.

As far as there being algae in the tank, there is plenty LOL. That was the whole reason I got the Sea Hare.