Rx=reactor.
I started with balling a couple of months ago after using Ca Rx's for years... Balling is a little more work overall, but it's nothing like equipment hassles with Ca Rx's, and I think it's so much easier to figure out your dose and dose itâ€"it's all just mathematics. It's not that big of a hassle with Ca Rx's, but it isn't as precise or easy as dosing the chemicals straight, trust me. Plus the benefits of ballingâ€"NEVER seeing my pH below 8.05, and not having any excess CO2 in my system, has been great (after years of seeing a pH of 7.8 way too often). Also, most Ca Rx's will add a little (or a lot) of phosphates to your system, which if you run the Ca Rx effluent through GFO's, or have a good overall nutrient removal plan in place, isn't a big deal.
For balling you really only need to order the calcium chloride and magnesium chloride by mail order. For the alkalinity you can using either baking soda or baked baking soda, aka soda ash, ($5 for 10 pounds at Smart and Final), and Epsom salts for the magnesium sulfate.
You do have to keep an eye on salinity, adding the chlorides will raise it very slightly. I just make my WC water a little lower to compensate. I also do true balling (as opposed to 2-Part dosing) and add 20 grams a week of Fauna Marine chloride free mineral salt (cherrycorals.com) to combat the chloride build up.
If your looking for cheapest in the long run, it's probably a Ca reactor, but you won't see the savings for 2-4 years. And you have to be prepared to research and learn a lot more, and get used to fiddling with equipment to dial in the Ca Rx at firstâ€"maybe fiddling a little, maybe a lot (depends on a lot of things ranging from CO2 needle valve quality, to how you feed the reactorâ€"slow flow peristaltic pumps are best for feeding). A Ca Rx is daunting at first to a newbie, a little confusing, and requires much testing and fiddlng, don't underplay this. Also, you need to be prepared for possible PO4's and lower pH and CO2 in the system, and many Ca Rx's owners have to dose a little alkalinity supplement as a lot of systems use more alkalinity than the Ca Rx can provide.
If you want the easiest in terms of set and forget, with much less equipment oriented issues, and much less money up front, it's balling. But you do have to keep track of salinity and WC's become much more important. I use 2.5 gallon jugs of the the alk and Ca solutions, and for my 90g tank they last me almost 3 months. I use inexpensive Drews Doser peristaltic pumps (bulkreefsupply.com, about $85) connected to my RK2 controller, that turns the pumps on for one minute sessions at certain intervals throughout the day. I simply lower the intervals between doses as the demand within the calcium carbonate grows.
If you do go with a Ca Rx (and GEO's are great), I highly recommend the coarse Gen-X media. It was the lowest in PO4 that I found....
