RO Water exclusively

OK, I'll have to add some tap water and test the carbonate hardness again before I do the WC today. Thanks for the help!
 
"When is it going to drop?" isn't the appropriate question as much as "What will heppen when it drops?" is

When it drops due to RO replacement, it may drop very quickly and it may do so only when there is a very low level of TDS, which will result in osmotic stress and pH instability.

Adding some tap & doing testing to characterize what/how much "stuff" is in the water is a good idea.
 
AquariaCentral.com