Raising Salinity

[nbraunstein]

I have a 125gal tank with a 40gal sump. I am using natural filtered seawater which should be around 1.025 but after pumping some out for displacement of my live rock and adding some freshwater in for evaporation my salinity has dropped to 1.022-1.021 I would prefer to keep it around 1.024-1.025 for a reef tank how much salt should I add to raise it to optimal levels? Should I just pour it in the sump right under the drain where it has the most water movement? Also what is the best way to properly keep my salinity at the my chosen level which dealing with evaporation and water changes?

Thanks,

[Randy Holmes-Farley]

If you have any of the natural seawater remaining, I'd just use that for top off water for a few days. If you want to use artificial seawater, then i'd make it up to about normal strength, then use that for evaporation top off.

If you want to raise the sg from 1.021 to 1.025, that is about a 20% increase in salinity, so you'll need to add roughly 15-20% of the tank volume in seawater as top off. If you evaporated 1-2% of the tank volume daily, that will raise the salinity in roughly 10-20 days.