I got a refractometer a few weeks ago and I have a 200gph and 800gph powerhead in the QTDon't do Hypo unless you have a refractometer. You also need either a nano power head or an air line (no stone). There is less oxygen in a SW tank then a freshwater one and you must have movement of the water for good gas exchange. I attach an air line to the PVC via rubbberband when I do quarantine or hospital tank.