what is kalk and how do you use it in your ato ?


New member
Im very new to sps I only have a blue milli and Im going to get a few ora corals but what is kalk?

I have been watching my calcium and alkalinity and I have had to dose B-ionic every couple days on my 12 gallon aquapod.

I know that sps needs calcium and alkalinity and mag. to grow and thrive but Im lost when it comes to all these dosing pumps and kalk ?

I have an ato on my tank I use 2 one gallon milk jugs and run air to them and pushes the water to the tank works great but I wanted to know more of dosing and stuff ?


Premium Member
"kalk" is short for kalkwasser or limewater, a super-saturated liquid high in sodium bi carbonate and calcium carbonate. A lot of reefers use this as their top of water to maintain proper calcium and alkalinity.
I would read up on a lot of the articles in the reef chemistry forum......tons of good info there.
As far as dosing goes, there are as many ways as there are months in a year. I personally use an aquamedic reefdoser twin which is a peristaltic pump that draws liquid from a reservoir and pumps it into my sump. this is for my two part solutions.
Others use different forms of pumps, calcium reactors, gravity feed set ups etc...... Do some research and see what you think will work best for you.

Good Luck with the sps!!!

Randy Holmes-Farley

Reef Chemist
Premium Member
Limewater (kalkwasser in German) is a fine choice, as long as the demand is not so high that it cannot meet it all alone. It is all I us eon my system.

These may also be helpful:

The “How To” Guide to Reef Aquarium Chemistry for Beginners, Part 1: The Salt Water Itself

The “How To” Guide to Reef Aquarium Chemistry for Beginners, Part 2: What Chemicals Must be Supplemented

The "How To" Guide to Reef Aquarium Chemistry for Beginners, Part 3: pH

The “How To” Guide to Reef Aquarium Chemistry for Beginners,
Part 4: What Chemicals May Detrimentally Accumulate