Yep.. It's been discussed and nope, that pump is not suitable for calcium reactor use. Stenner pumps are not designed for 24/7 continuous duty. Nor can they be slowed down enough to meet the flow requirements of a calcium reactor. You really need a pump that you can control the ml/min rates very precisely and one that can pump continuously down to very low flow rates. +- 25ml/min. While you can adjust the flow on certain models, the motor spins at a constant speed but the adjustment controls a clutch that changes the frequency that the pump head engages in. The end result is that the motor never slows down. They are also TERRIBLY noisy. FWIW, I run a Stenner 85M5 for my ATO pump and they are probably the best ATO pump money can buy but I would never even consider using one for a calcium reactor as they don't offer the kind of precise control needed for calcium reactor use and would also result in flow irregulatities due to the fact that flow isn't constant if you slow them down. Instead it's intermittant due to the pump head clutch engagement.