Lostmind, I will test 1 night without the skimmer on.
Bev, I've recorded the oxygen % in the room's air. Before I go to sleep, it is 100.3%. When I woke up, it was 99.8%.
LINK
I also tested the tank's DO this morning after I changed the airstone in 1 of the skimmers which allowed it to start collecting skimmate again. I dialed up the air output of my optima pump. I added new Kalk to my kalk dispensor. The DO reading this morning was 58.2%, PH was about 8.0.
LINK
Sorry, I forget to measure in ppm again. Just for clarificiation, when DO in measure in percentage, temperature is accounted for. When measured in ppm, temperature is not accounted for. Right Christy?
Welcome to Canreef tatuvaaj. I'm hopeful that this thread will be useful to you.