I know this is an older thread when it originally was started. Perhaps by now you have made a decision so take this for what it's worth at this time. I recently purchased a full blown calcium reactor package. I used a reactor roughly 13-15 years ago and swore I would never purchase one again! Waay to finicky to adjust with needle valves, feeder pumps etc. Today I have a larger system with all sps. The calcium and alkalinity demands were becoming cost prohibitive. I was purchasing 4 gallon 2 part monthly and although I have the time to manually dose (I have had issues with dosing pumps as well) I finally got tired of dosing and needed to move to a reactor to keep up with demands. I did a lot of reading and had decided on a Dastaco. Problem was I couldn't get one for months for they were back ordered. Gave me an uneasy feeling if a problem arose how long until parts would be available. I had dealt with overseas manufacturers before and it wasn't always good. Personally I chose a Geo reactor with a second stage, a carbon doser regulator and a Masterflex pump. Expensive...yes...however I need a unit I can trust to run consistently if I'm out of town etc without worry of inconsistency of breakdown. I consulted a group of reefers and not one had a complaint of the combo. So far I have been pleased with the units and quality AND if something goes wrong everything is here in the states. Gives me more peace of mind.