Here's a super cheap method, Rubbermaid Tub with float valve, a hole drilled in the bottom with 1/4" poly tube feeding into a 5 gallon pail with kalk with an airline check valve so i don't run kalk into my rubbermaid tub if it's more empty than the kalk. Then gravity fed to the tank with a float valve in there. It'd behind a door, so didn't care how it looked. Works great, only issue i've had is after i moved the Kalk bucket onto the same shelf i have to restart the syphon if i let the rubbermaid tub run empty. I usually leave my RODI on since I have an auto shutoff on it, but recently i've been turning it off since I don't check on it as much as i used to and would hate for there to be an issue one day.
I wasn't running kalk for the first year so had the rubbermaid tub feed straight to the tank's float valve. Now i've been using kalk and loving it, onlt thing i hate is that i add kalk when my PH is already high during the day when i have the most evaporation. I've ordered a solenoid to shut it off during the day and just top off at night, then i should be happy as can be.
Ignore the wires on top of there, i'm changing my temp probe out and left it a mess. As the same with the 3 part pre-mix bottles :P. I really need to do some tank housekeeping....
