Wanting a clam...

The concern about needing the reactor steams from the fact it's only a 20 gal tank. The clam could use up quite a bit of the calcium in short order. If you closely watch things for a while you'll find the dosing balance though.

A clam in a 20gal is quite different from a calm in a large system (say 100+ gal), where regular water changes may be sufficient to replace the lost elements.

 

I got ya. I'm probably going to be adding a sump, and I think I'm going to follow one of my local reefer friend's plan. He has a 75 gallon and he changes 1 gallon every single day without fail, and then changes 10 gallons once a month. I think with my 20 gallon I could do a quart a day (mainly keeping the minerals up, and pulling some nutrients out) and then do 2-3 gallons occasionally. The reason he does the gallon per day is its super simple. He has a valve on the return line and when its turned he can divert some water to a separate hose, to a jug, and then down the drain, but with only losing a gallon he doesn't have issues with having to turn off the return pump or anything. as he says "its like doing an oil change"