32 gal brute, into which I dump a pound of kalk the first of the month.
It has a dual-float connected to a solenoid that activates my RO/DI. I have the float on a timer, to prevent possibility of overfilling. It is set to fill the bin tu/th/sun. 15min a day an MJ1200 with Sure Flow kicks on to stir. That's the "in".
Out I have a Chem-Tech (reef-filler) pump set to drip to match evaporation. So all topoff is kalk and it is continuous. I used to have a timer on that, now it's on my Apex, and is off for an hour midday and midnight. At one of those the MJ goes on (don't recall which anymore!)
Note -- the Chem-Tech can be pricey. But I found on on the bay for under $150. Does 15gal a day max. But you don't have to have the same as a reeffiller. Hanna now makes a metering pump for around $100 that looks very good. LMI pumps are all over the bay and elsewhere and can be had for that. They'll all do the same thing.
I like the pricier Chem-Tech because it is self-priming, so I know that if power goes out it will go back on. I like the comfort but you pay another $50 for that.
No idea where Wilmington is but you are welcome to come by to see with eyes if you want.