Raising Ca in WC water?


Junior Member
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So yes I know everyone is telling me to use kalk :) but until I figure out all the logistics of doing that I have this question.

I'm using IO salt and ro/di water. We usually change out 15g every other week. Have found out that my fresh IO salt water only gives me 300-350 Ca level. I usually make the water, add salt & then let it sit with a heater and power head to circulate for 2 days in a rubbermaid bucket before doing the wc.

I've finally gotten the tank to a Ca level of 400-450 by slowly adding Kent liquid Calcium. And then two part to maintain. I'm thinking though that as soon as I do the wc the Ca level will plummet. Is that just par for course? Or should i possiblly treat the wc water to head this off?

Thanks for your input and my apologies if I'm missing something here.


Active member
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Hey minyee...besides your Ca levels, your Alk levels need to be monitored as well. They have a very dependent and needs a balance relationship. Try searching for some threads here and/or on google. Also, I would suggest gettings accurate tests for both. FWIW, I add a cap of Reef Complete to my weekly make-up water and this seems to be keeping things balance.


Fish and Coral Killer
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You can bring the Ca level in the new water to match the tank water, I do that when I do large water changes(20%) by using Dow Flake. Watch your Alk and Mg levels like everyone else suggested, these will screw up your Ca level too.