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. 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.