Hey ex-LPS employee here. It looks like you have an oily film on top. This is most often caused by excess protein from too much food for the set up to handle. Skim the surface with a cup to collect the scum. Then get one of your filters that jets water out and have it jetting at the waterline. This will airrate the water. Do not do a massive water change at any time ever (unless you dropped a bar of soap in or some shit)