I'm thinking you would have no issue with 5in of water as long as the pump is submerged fully. I think something in the water is triggering it to foam a ton/overflow. If running it at that level for like a few skimmer cups full and it still doesn't settle then u may have some other issues... but cross that bridge when u need to
I will raise the skimmer again as suggested by you and David Drew and see what happens. It will have to wait until Tuesday or Wednesday as I won't get home early enough to mess with the tank before then. I'll let everyone know how it goes after running it a few days at that level.
What's the health of your tank like? Algae? Nitrates and Phos? Is it possible that your water is just dirtier than you think and the skimmer is reacting appropriately? I could see this happening in a new FOWLR with uncured dry rock maybe
I'm guessing you just have a lot in the water you need removed. I would raise the skimmer until you get a reliable skimmate and slowly lower it as the water cleans up. As long as the pump isn't sucking air it shouldn't affect it.
Hi bean, I did not use uncured rock, but I did use some well water and purifier when I set up the tank. I have two Marine Pure blocks in the sump along with various small pieces of rock. I have about 50-75 lbs of live rock in the MD, and I added one bag of live sand to seed a 3" bed of sand (I have wrasses and an engineer goby, so a deeper sand bed is needed). I've decorated with various artificial decorations that were taken from the 75 gal tank, sterilized, and rehomed to the 180 gal tank until I can afford more rock. My nitrates are high at a little under 20, but I'm due for a water change. I like to feed heavily, so I have to do frequent water changes. I rinse all frozen foods before feeding the tank to help cut back on phosphates, but I don't usually check for phosphates in my FOWLR tanks, just my BioCube, which has coral in it.
I will raise the skimmer as suggested and see what happens.