Toxic bubbles in sand

[Tate]

There are bubbles In my sand bed and they create a weird film on the top of my water daily and I have to aim a powehead at it and force it to the overflow. Are these bubbles the source of my nitrates??

[54seaweed]

you should always keep a ph aimed at the surface
for surface circulation as for the film your skimmer should remove it
if your getting lots of those bubbles you need more sand sifters yes those bubbles can be toxic if you allow them to build up

[Tate]

Well my I have to get my nitrates down before adding any more stock and my protein skimmer is not the best and hasnt really worked yet and my return pump is pointed at the surface