What to do with left over water change water

[Reef.]

I think it’s a good idea to wipe/rinse the barrel every now and then anyway. It breaks any bacterial chain that mind be going on in the barrel.

A lot of salts can leave a slime/residue, I’ve just moved from Red Sea, it left a slight brown residue in the barrel, not bad for me, but some seem to suggest it’s a bit more for them.

 

[Arricefe]

I make enough RODI water to do a 10% water change and fill my ATO, I “save” 5 gallons of my “old” water in a jug ”just in case” and dump the rest down the drain, if I don’t use the 5 gallons by the next water change I dump it and start over.