Kalk is king in the saltwater tank additive world. For you reef enthusiasts and reef junkies, its a must for your tank.
However, it is very potent and can ruin your whole tank if you don’t follow these steps:
#1: NEVER add it directly to your tank.
Kalk has to be dissolved in RO/DI water, NOT added directly to your tank water. If you add it directly to your tank, it will precipitate calcium immediately which means your tank will look like its snowing. Not good.
#2: Use it in your top off reservoir not a kalk reactor.
When you add kalk to your top off water in your reservoir, then you can adjust the concentration of kalk going into your tank. If there is too much kalk in your reservoir such that your tank’s pH and Alkalinity are going up too much, then you can add more RO/DI water to dilute the concentration. If it isn’t raising your pH/Alk enough, add more kalk.
My issue with kalk reactors is that they dump in 100% concentrated kalk to your tank. This is a problem during the summer when you are toping off a lot due to the heat. More top offs with concentrated kalk means more drastic pH/Alk swings, which means your corals won’t be happy. I helped a reefkeeper who had a kalk reactor and his Alk was swinging between 8 and 10 during the course of 12 hours. This is WAY too much and his corals started bleaching out because of it.
Plus, kalk reactors can be expensive. You’ve already got your auto top off setup (if you haven’t, you need to ASAP) so that part of your tank is already paid for!
#3: Start slow and increase the amount you add slowly.
Every tank responds to additives differently so when you are starting to add kalk to your tank (remember to add it to your reservoir, not directly to your tank), you’ll want to start with a low concentration – 1 teaspoon/gallon – to start. Run that concentration for a couple of days and see how much your pH/Alk swings. You want your pH to rise no more than .02 whenever your auto top off (ATO) runs. So if your pH is 8.00 when your ATO kicks on, after it kicks off, you don’t want your pH to be above 8.02.
Increase the amount of kalk in your reservoir until your pH rises more than .02, then back off 1 teaspoon/gallon. Keep note of what level your Alkalinity stays at as this level will be your “baseline”. Any reading above or below it and you’ll need to revisit how much kalk you are adding to your reservoir.
#4: Seasonal changes will affect how much kalk you add to your reservoir.
During the summer months, you will use more water from your ATO reservoir, so you’ll want to decrease the amount of kalk to you add. In the winter, the opposite will happen. You’ll use less water from your reservoir, so you’ll want an increased concentration of kalk.
Having your baseline Alk values in place outlined in #3 will let you know how much kalk to add/not add.
For my tank, I add 4 teaspoons of kalk per 5 gallons in the summer and 7 teaspoons per 5 gallons in the winter. My Alk stays @ 8 year round.
I cannot say enough about kalk and how much it keeps your tank’s levels in check. Like any potent tool though, it must be used carefully. If you start slow, then you can’t screw it up. Add too much too fast and your corals will bleach and your tank will suffer.
Use kalk wisely and watch your tank will thrive.Browse the Store! Questions?