Hi Lasse, thank you for your post! I had quick glance at your thread. Just awesome! About flow in the sponge section, coincidentally, I put a small water pump to agitate a bit. I stop my wave flow at the main tank once or twice a day so that my slow-eating mandarinfish can eat things at the bottom of the tank. But when I do it for 10 minutes, gas exchange in the sump is lost. I wanted to prevent it. Lasse, I don't have Apex system. So I can't do 24H monitoring, but I'm very curious about monitoring maybe once in 4 or 5 hours. I use the following test kits. NH4 Tetra NO3/NO4 Red Sea PO4 Hanna pH Tetra I would like to replace those Tetra kits. My Tetra kits could be too old. So I'll have to start from searching alternative test kits for NH4 and pH. I have zero chamical knowledge, and I can't even do the guess work. So all I can do is just test. But if you can help me out from the data I got, that's great!