Ok thanks for the tips, I am able to be pretty diligent with top offs as long as its like once or twice a day, hopefully not multiple times a day? And I don't have a tap for water any where near my tank if a top off device requires one...
For topping off I just need to add fresh, correct?
Which leads me to another question. RO or tap? Tap would obviously be easier, but I can do RO also. If RO if highly recommended, I'll do it, but what do you add to make it marine condition, ph/hardness buffer?
Use RO water. Your salt mix will buffer it.
As for the top-off devices, most of the homemade ones I've looked at online used a container full of freshwater rather than a direct connection to the water supply. All top-offs should be done with freshwater.
