Hydor Slim Skim Nano only working during lights out, running 24/7

[CoralRehab]

I love this new little skimmer and the bubbles are super small, but I'm wondering if anyone knows why it skims well with a nice head of skimmate until the lights come on? Once my lights fire up, the skimmate drops all the way back to the surface of the skimmer.

 

Ideas?

 

 

Could dosing NaHCO3 or Vodka cause this behavior? All other settings stay the same throughout the day/night except I need to test for pH Swing.

 

dKH 8.9 (.2 drop over night)

 

CA 450 (25 drop in 3 days from 475)

 

Mg 1350

 

Vodka .2ml/ 22 gal/ split into 3 doses during daylight

 

NaHCO3 1/2 tsp diluted to 120 ml dosed throughout day (I'm switching over to the 1/5 baked, 4/5 straight mix to stabilize any possible pH impact tomorrow and see if that helps.