I agree with a Ca Reactor since I also wanted to automate some of my husbandtry in on tank. I have 75gal with a 55 refugium that's SPS HEAVY! And the constant adding of BRS Ca, ALK, Mag (daily) was creating a comstant swing in parameters which wasn't allowing the corals to really grow as in a stable condition tank. I was going to bug a doser whose price was the same as the AquaMaxx S2 Ca Reactor I purchased but I did math. I calculated how much in Ca, ALK, and Mag I would have to mix and keep ready for my doser, plus maintenance (that needed on any equipment) and replacement cost and possible errors and breakdowns.
My end decision was a Ca Reactor and its been just one of the best decisions I've made since setting up my tank. It's been running now for a year and after 10monrhs am I just cleaning and adding my media to the reactor. I purchased additional tubing or drip line from BRS (cheapest I've found) and change out the tubing if it needs it or not every 3 months and clean the drip valve. I bought a 20lb C02 from someone locally for $80 and two 5lb for $15 ea (did a WTB C02 tank on local forum) and cost me $40 to fill all three. At the current I won't need to fill the 20lb for another 2yrs and 5lb are my back ups.
Ca Reactors are very easy now to run and maintain IMHO just as dosers are but I like the fact that I'm using really coral to feed my tank that's not man made and I don't have worries that I get a (Bad Batch) and have to complain to the company about it. You can have issue with Ca Reactors like I cleaned my sump and did pay attention where my intake line was for the reactor and it was exposed to air which filled the reactor. Some would have panicked but I treated it just like when I first set up the reactor. I turned off the C02 opened the effluent wide open of course made sure that inline was back under water haha and let it running till all the extra air was cleared out the reactor. I then let my Ph in the reactor reach its highest point (7.99) then adjusted the Elluent of drip to a three drips a second then turned my C02 back on and adjusted the reactors Ph till it reached 6.60. All this took 4hrs and the tanks Ph, ALK, Ca, and Mag never swing.
That's my feeling on if you chose to invest into a Ca Reactor and if you chose to ease feel free to PM me if you have question I set several of this up a month for other reefer and be glad to assist if you need it.