pH/Salinity Conflict

ubiq · Apr 29, 2022

I use a kalk stirrer to maintain an 8.2 pH. The problem is that the amount of kalk being fed is lowering my salt to sub-32 ppm, even with the ATO turned off. Salinity has been as low as 30.2 in the morning. I've been trying to compensate by using a hyper saline daily water change, but it's a hit or miss solution. Anyone else run into this issue? Corals seem healthy, but I'm worried about the fish.

BanjoBandito · Apr 29, 2022

It sounds like you are overdosing your kalk and adding too much limewater which is throwing your salinity down/diluting it. I run a kalk stirrer and I'm a "kalk guy", but you might want to look at another way to manage your PH. If it's taking that much kalk to maintain 8.2 (reference I dose 1000ml a day of limewater in a 106 gallon system and my PH is 8.4 - but I also use a turf scrubber) something else is holding that PH low. Maybe look at a CO2 scrubber attachment for your skimmer?

Garf · Apr 29, 2022

ubiq said:
I use a kalk stirrer to maintain an 8.2 pH. The problem is that the amount of kalk being fed is lowering my salt to sub-32 ppm, even with the ATO turned off. Salinity has been as low as 30.2 in the morning. I've been trying to compensate by using a hyper saline daily water change, but it's a hit or miss solution. Anyone else run into this issue? Corals seem healthy, but I'm worried about the fish.

Lol, what’s happening to your alkalinity?

ubiq · Apr 29, 2022

Garf said:
Lol, what’s happening to your alkalinity?

dKH runs 10-13

Garf · Apr 29, 2022

ubiq said:
dKH runs 10-13

What corals have you got? That’s a heck of a swing.

Randy Holmes-Farley · Apr 29, 2022

In general, the daily evaporation limit is the max amount of kalkwasser you should be adding to the tank, otherwise salinity will be impacts as you found.

markwayts · Jul 26, 2022

I always wondered if you couldn't just fill your kalk stirrer from your display tank instead of from your ato.... like with a dosing pump. Even if the saturation point is lower you can turn up the flow to get as much alk as you want.

Randy Holmes-Farley · Jul 26, 2022

markwayts said:
I always wondered if you couldn't just fill your kalk stirrer from your display tank instead of from your ato.... like with a dosing pump. Even if the saturation point is lower you can turn up the flow to get as much alk as you want.

No. Magnesium hydroxide and calcium carbonate will precipitate in the reactor.