the reason i aksed is because after i added my order from reef cleaners my fish , well, a couple started acting funny, maybe they just got stressed out becasue i was in there some, but, i have had my skimmer turned off for 2 days because i am treating for ick, but, i turned it back on becasue i think my oxygen was getting low. i have a 110 gallon tank, and all my perimeters are perfect. so, i think the skimmer turned off maybe made the oxygen level go down, it produces alot of oxygen in itself!