skimmer overflowing

[foxhuntr]

I have a Vertex Alpha 250 skimmer running in my sump....i have been having a very hard time getting it tuned in...i noticed for about the last 2 weeks that it over flows only at night .....i have a DIY skimmate locker with a float switch in it so it shuts the skimmer off if the locker gets full...well ever morning i wake up about 3am and take a peek under my stand and the skimmer is shut off...so i drain the skimmate locker and the skimmer comes back on and it is overflowing like its way out or adjustment....it runs fine during the day when the lights are all on but at night after the lights are off it goes crazy..i even noticed in my filter sock the water running into it is alittle foamy in the sock......what is going on ? Its like someone puts a drop of dish soap in my tank every night. It has to have something to do with the lighting or algea growth or something.....can anybody explain to me what is going on?

 

[DFW]

Are you dosing something at night? Are you topping off at the end of the day, or adding anything at the end of the day?

 

[Reefing Madness]

Do you have any corals that might possibly be spawning?

 

[foxhuntr]

No i am not dosing anything and i have a ATO so my water level never changes.......not sure about any corals spawning