Welcome to FMAS!
A reactor will be for you if you do what everyone should do regarding equipment but never do, which is to buy once, and buy right. It's worth spending a bit extra $$$ the first time to do it once and do it right, versus buying something cheap, then either it breaks, or you demand more than it can give, etc. That being said, the best two reactors as far as consistency, quality, and ease of use, are Deltec and Geo. There's a price difference, but they do have different qualities. I don't think anyone can compare these two brand's reactors to anything else, as they're just the top of the food chain as far as readily available non-custom reactors go. Not to mention that you can pick a used one up for a bit less than they are new, save some money, and still have a fantastic quality instrument.
A reactor is for you if you're willing to dedicate a week to set it up and willing to spend the money up front for quality equipment. Other than that you likely won't need to futz with it all the time. Maybe check your CA and Alk monthly, bi monthly, 6 monthly? I know I don't check mine but bi-monthly, mostly because I'm not around to check it. I set up my reactor, and don't adjust it unless it's clogged up (which happened when I had crappy feed pumps, doesn't happen anymore), or my corals uptake demand increases (which happens every year or so).
Will it save you money?
You're currently using 220ml per day. If you buy a two part kit from TPS, it's $12 per 2 gallon kit (1 gallon of each part), 1 gallon is 3785ml, and 3785/220=17. So you'd get 17 days worth of 2 part for $12, which is $12/17=
$0.70/day using TPS's pre-made bulk kits, roughly $255.50 per year on just the 2part. And that didn't include shipping, but the cost of the shipping is probably offset by the fact that you probably buy in larger cheaper quantities than stated above and priced on their site, maybe, so it's variable unless I know the inputs exactly.
Using a Deltec Reactor, you'd pay equipment cost up front (depends on size of your tank, if you buy used, etc), but you'll probably use only about one reactor change worth of material per year. So you've got a bit less water volume than, I, but should probably go with a similar sized reactor. I have the PF501, rated for a 280g tank, but is quite sufficient for my tank loaded to the brim with SPS. So on my PF501, I have to add another change of media once a year, maybe even every 9 months. An irritating process, because you've got to take the reactor out, but not a huge deal. I fill it back to the fill line at 6lbs of Deltec Rowalith C+ media, which goes for $40 for 10lb (MSRP). since I fill 6lbs per 9 months of heavy use approximately, let's just say I use the whole 10lbs in a year, so $40.
So we're at $40 per year for a Deltec reactor (excluding cost of pump electricity [small power consumption] and cost of shipping of the media, which could be offset by buying in bulk or buying for cheaper than MSRP, not sure if anyone sells it cheaper, I've never had to buy a new bucket)
Now, 2part cost you $300 upfront with a Leitermeter3, plus any tubing you've had to change, but for simplicity's sake, let's say just $300.
The Deltec reactor will set you back $600 for the reactor, $150 for the pH controller (or don't consider that if you've already got another controller, which it sounds like you have), and $100 for the CO2 tank and regulator, which needs to be filled about yearly (in my experience). So $850ish
Now, you'll have $300+the cost of media per year, which is $255ish, so first year you'll have spent $555, second year you'll have spent $810, and by the third year, you've spent $1065. For argument's sake, by year 6, you'll have spent $1830. That's a lot.
With the Deltec, it's $850+$40 for the media/year+$20 for CO2 fills/year. First year you're looking at $910, second year it'll be $970, third year, $1030. Just for argument's sake, 6th year you'll have spent about $1210.
Now, it all depends on how long you plan to be in the hobby for, how long to keep these corals, demand changes, a lot of other confounding factors. But you can see the price over time.
The Deltec will NO QUESTION keep up with your reef. The nice thing about the Deltec is that the media it uses can apparently withstand much lower pH in the reactor without melting, so you can squeeze more CA and ALK out of it. I didn't know that until someone told me in a Deltec forum, on why I should use their media over another company's. The Geo will use ARM large grain media, which will run at a lower pH than the ARM fine grain that most reactors use by standard, but not as low as the Deltec. So you can squeeze a lot out of it, but not as much as the Deltec. The only reason you may ever need to add a drop of 2 part here or there is to balance out an imbalance in the tank's uptake of one property or the other. different corals can uptake different amounts of each, CA or ALK. You can also have magnesium taken care of if you add 10%ish of your total reactor media volume as Dolomite rocks (which I've wanted to get for mine, as I'm manually adding magnesium occasionally from Randy's Magnesium 2part right now, but only needs it every year or two)
As far as consistency, the two reactors mentioned are rock solid once dialed in, and they should be controlled with a pH controller as stated above, with a solenoid on the CO2 setup, which will keep it consistent as well. The output does fluctuate over time as the media is dissolved, but in my experience, I have not noticed a difference in tank parameters. Honestly I don't check them much anymore anyway. I may check every 6 months the nitrate, phosphate, calcium, and alkalinity. Every year I check magnesium. I check the salinity whenever I do a waterchange or trade frags or something, to make sure my added water doesn't throw off the salinity.
Every reactor NEEDS the pH monitored, at least occasionally or until it's set up and dialed in. People have mentioned before that you can adjust the ratio of calcium to alkalinity going out of the reactor by changing the pH or flow or something like that, but I've never looked too much into it, and I haven't had a problem. I have some corals that would grow out of the water if the intensity of the lights above them didn't keep them down.
Is a reactor for you? I've done my best to answer that question. I certainly hope it helps. There are too many confounding factors for me to be able to give you a definite answer though.
