High Carbonate Hardness

[johnwhite1989]

Im new to salt water aquariums and have only had my tank set up for two months now. Today when i checked my carbonate hardness it was at 14 dKH or 149 ppm. I know thats higher then normal but my PH is right were it should be so is high carbonate hardness a bad thing or is it just low hardness i should care about? Also ive been adding kawasser to my tank because calcium is low at 340 ppm so can the two problems be related? Thanks

[FoMoCo Master Tech]

High KH will drive Calcium down, like you're experiencing. Using kalkwasser raises both Cal and Alk. The important thing about reef chemistry is to have Calcium, Alkalinity and magnesium within normal ranges AND balanced with eachother. Not only does it keep Ph in Chechen, but its important for healthy growth of corals, inverts, etc... The easiest way to do this is by using a 2 part suppliment ( which is actually 3 parts). The difference between a two part and individual additives is that the two part is ionically balanced so the Cal and Alk wont drive eachother the opposite way. This link: What is Water Quality explains water quality in great detail and also has a nice chart, showing balanced Cal, Alk and Mag levels. Calcium, Alk, Mag, temp, salinity, Ph, ammonia, nitrites, nitrates ( if its a reef tank or a tank with inverts) and phosphates are the most important in keeping a healthy tank.

[Original Fin]

+1 on the 2 part method.

What you're experiencing is a Kalc overdose, and it's real easy to do. Kalc dripping can work, but it requires constant testing and modification of dosages...and the delivery method needs to be bulletproof and foolproof. It's pretty easy to make mistakes with that method, and most people doing it for the first time tend to ignore their magnesium levels, and that can be a big mistake.
Most corals will start to react unfavorably at the range your currently at and above. I'd shoot for a dkh around 9.6, but on a new tank run by a new hobbyist, wouldn't really sweat it as long as it's between 8-12. So for you, I'd stop dripping the Kalk. Wait for your alk to come down to whatever target level you want to use. Wait a week from that point and measure again. Record how much it dropped in a week, and dose accordingly. I do mine daily, but on a new tank you might be able to get away with once a week. You just don't want it to drop below the acceptable reef ranges, which can be found in the link FoMoCoTech provided earlier.


As the tank matures, the life contained within will progressively consume larger quantities of cal, alk and mag. Especially if you keep a lot of stony corals. 2 part dosing is a pretty easy method of keeping up with this for most hobbyists. Calcium reactors are another method, but that's for the advanced hobyist. It requires a significant investment in equipment...CO2 tanks/regulators, reactors, PH & CO2 monitors/controllers, etc...Usually you see these on very large SPS tanks with very large consumption rates. The 2 part method would actually cost more in the long run to maintain on those very large systems than a Calcium reactor would, but reactors are a big initial investment in equipment.

Hope this helps, and welcome to Reefland!