Thank u. I have a jebao 20000 so with 6 feet of head and 3/4 returns I am hoping for 2000- 2200 GPH and yes for now if I need to add more I have an FX6 I can put on too. That will be on the tank only for cycling. I have had that on my other tank that is going to come down. I started out with a 400 gallon tank and ended up with a 600 gallon tank. I know 3.8 to 4 times turnover is on the low side but I am hoping with over 400 pounds of rock, an algae scrubber made with a 20 gallon acrylic tank, and the biggest denitrate filter I have ever seen anyone make. It is going to be an 8 round inch pvc and about 5.5 to 6 feet tall. I have Marine Pure blocks, and some of the other blocks that a company that make blocks like MP. I have used the MP balls and they worked amazing I dubbled the time between water changes on my other tank. plus I have a full C2C so I have my fingers crossed. I want a bigger sump that is only a 80 gallon frag tank that I have had for years. I would like to go to a 125 ,150 or 180 but my stand is low because I had to be able to fit it through my doors so it is only 30 high so I do not have a lot of height to work with. I dont know if this will even hold all the water in a power outage. I can buy a 125 with stand and everything from petsmart for $425 so we will see.