Seems like a lot of water splashing out of the skimmer outlet pipe, any micro bubbles in your main tank? If so either fit a sponge to the outlet or stuff a piece of sponge on the last partition before the return pump. Foam level for the skimmer seems a tad too high also, just a cm lower would be best to get semi wet skimmate. Check your salinity also as it effects skimming, maintain 1.023~1.025, if fish only setup 1.021