[sphelps]

Thanks untamed, I actually was just running the skimmer at night and not during the day to avoid low oxygen levels at night. However I did just figure out the problem and it was a result from low oxygen.

I remembered I did the final programming on my controller yesterday, what I wanted was the skimmer to act as a timer and only run at night but I also wanted it to turn off during a "feeding pause" because I would be feeding the corals more at night. In addition I wanted it to stay off for another 30min after the feeding pause ended. I used the programmable logic to to combine the timer with a delay on set to 30min and then all I needed was the timer to shut off during a feeding pause but I couldn't do this with the programmable logic. So I noticed a check box under the timer which said something like "active then feeding pause", now keep in mind that profilux language seems to be mostly translated from German so it's not always clear, I automatically assumed that checking this box will insure the skimmer will shut off during a feeding pause. Similar check boxes are attached to other processes and I've used them before with success.

Unfortunately I was wrong, by checking that box I told the controller to activate a feeding pause while that timer was active and for as long as that timer was active! So last night at mid-night, while I was sleeping, all my pumps turned off and 30min later the skimmer turned on, which overflowed with the higher sump level. The pumps remained off until noon today. The fact that this happened over night with all the livestock I have must have completely diminished all the dissolved oxygen in the display while the skimmer helplessly filled the disconnected sump with foam.

So Mr OM, you were 100% correct, it was an engineering problem. A problem resulting from the stupidity of this engineer who didn't check his programming which resulted in the death of very creatures I designed this tank for. I take full responsibility but the one thing that blows my mind is that the profilux will not allow you to set a feeding pause longer than 20min yet it will allow a timer to activate one for as long as you set that timer for. That is one dangerous check box, users be warned.