honestly, I don't have a better option than using R/O water instead of tap water. Most salt blends, even Instant Ocean, will make good R/O water have an alk
of 2.5-3.0 meq/l if you're mixing at their recommended levels (IO is 1/2 cup per gallon, 1.021 SG
That's why I'm assuming you're using tap water. If you're using R/O test it's alk
...it should be next to nothing...if it's not it's 'bad' R/O...the resin cartridge is old and needs to be replaced.
I'd test your water first though (the source water). See what it's at. If it's a lot lower than 11 dKh
, you might just be building up alk
over time. Only H2O evaporates...the minerals that are alk
and general hardness remain behind. Topping off with mineral rich tap water adds more hardness over time. Thus you concentrate them. R/O water should be mostly void of any minerals, and thus topping off with it will dilute the hardness.
If that's what's happening on your end, you'll need to do lots of small water changes, preferably with r/o just for the stable alkalinity. Then once it's back in check, you can just do top-offs with R/O.