I'm using a Sicce Syncra Silent 5.0. It's the perfect amount of flow for the tank in stock form. However, not that I have added the reactors, I think I'm going to switch out to a Sicce Syncra Pro 1900 to get back to the same flow I had with the Silent 5.0. At the moment, RO water comes directly from the basement and plumbed into the stock float valve in the sump. I obviously don't trust the float valve in salt water, so I have a shut-off valve in the sump area. I just open the valve every couple of days and set a timer for 30 minutes. I still need to figure out what I want to do for a fail proof ATO. I'll get full shots of the sump soon.