Alright so been trying to step through some logic today but figured I would see if I can get some input from others…
While I wait for my fish to arrive I haven’t been nor do I plan on doing any water changes after the big 30% I did 2 weeks ago. However since ATOs only put in RODI water you lose some salinity over time. This logic all makes sense to me, what I’m trying to determine is the best way to make adjustments to said salinity to get it back in line? I have dropped from 34.6 to 34.3 in the last I don’t know 2 weeks probably just from the evaporation and salt getting out on the top etc.
Logic would have it that the best way to adjust this salinity is slowly and by adding pre mixed saltwater, however, my confusion comes in with how you know how much to add. I get the initial jump and waiting a few hours to measure it, but this doesn’t account for the evaporation that will then occur and not be replaced by RODI right away. If I add 5 gal of saltwater to my tank let’s say, the sensor on my ATO will need to lose that 5 gal and then drop before it finally adds RODI back in! This however since I would be adding saltwater would leave the salt behind without diluting it. Raising my salinity, but how in the world do you even account for something like that? The issue is not pressing since my salinity is still pretty good but just trying to wrap my head around stability before I start doing the weekly water changes?
Most of your saltwater will be lost via the skimmer collection, and any filter cleaning/changing where you’re pulling something wet out of the tank!
to top-up salinity, I usually add a smaller volume of saltwater; say, a gallon or two to the sump, then let evaporation correct my ATO water line over the course of the day!
I check salinity the next day, and have a benchmark for how much salinity X amount of saltwater adds to the system!
It’s also worth noting that double-checking salinity at each test is always wise… (also, more saline water does sink in the water column, I usually take my salinity test from a high flow area!)
