Kalk: how to: why to: how much to

Why put lime in your ATO?
It's called 'dripping kalk', from the German word for lime. It's appropriate for anyone with clams or stony coral, ie, a tank that sucks up calcium faster than weekly water changes can supply it.

This is why stony coral keeping is a lot easier than people think it is---easy, as in, "very little work"...as in, "actually far less work than keeping a FOWLR."

First you need an ATO [automatic topoff]. Everyone does who doesn't plan to spend life tied to a tank putting teaspoons of water in. And if you want to keep stony coral or clams and run this kind of topoff, a high evaporation rate is a real asset.

Dripping kalk can completely satisfy a coral-packed tank of 50 gallons, no problem. It probably can do the same for a 75. When you get above 100, it's a question related to how packed you are.

But here's how. You have an ATO bucket. Arrange for one with a lid. I used to use a 7-gallon Oceanic salt bucket [free]; I now use a 32 gallon Rubbermaid Brute trashcan, with rolled-up paper towel for a gasket to make the lid fit snugly. You also need to set your ATO pump a bit off the bottom: set it on a rock, eg, to keep it from sucking up any residue. I use a Maxijet 1200, and since the kalk-drip goes into the fuge area of my sump, I used reducing connectors to reduce the hose size from 1/2 inch to airline diameter: a locline connector hoseclamped inside the end of the 1/2" hose does the job. A metal hose clamp is ok inside the ro/di container, because fresh water doesn't care.

Now the nitty-gritty of how to run it. Understand two things. 1. kalk can only MAINTAIN the level of calcium you set. It cannot raise it. 2. it's pretty safe---if you have a topoff accident with it, your tank might turn white with kalk, and it will spike your ph a bit, but the real danger will remain the amount of freshwater you shot in via topoff. You can use a teaspoon or two of Schweppe's Bar Soda to lower the ph a tad, BUT since in such an incident the ph is going to fall back to safe level on its own PDQ, you risk overdoing it.

So: to set up: dose your tank the regular way, by hand, to the following readings: magnesium 1300; alk 8.3-9.3; calcium 420 or a little higher---in that order. Remember you can't add alk and calcium with 8 hours of each other.

Now: for a light coral load, you can try adding 1 tsp of kalk per gallon of reservoir water to your ATO reservoir, and lid it. Test your levels weekly. If they stay up, that's all you need. If the levels go down, correct your tank levels by hand dosing, and increase the kalk dose in the bucket to 2 teaspoons per gallon of ATO water, lid, and continue dosing.

2 teaspoons per gallon is the max you can do. Any additional will sink out of solution and lie on the bottom until you add more fresh water: this is why your pump is sitting on a rock. It doesn't go bad: in my 32, I dump in 2 pounds of kalk once every few months, and add ro/di as needed.

[If you are a 100 gallon borderline for being able to use kalk instead of going over to a calcium reactor, there is a way to hype this dose a tad by using white vinegar, but go to the chemistry forum to ask that one: I don't want a flock of word-of-mouth new users pouring white vinegar into their nano reefs!]

This system, with adequate light and a not so great skimmer, lets you raise really happy clams and large polyp stony coral with, as aforesaid, far less work than you think: no filters---these systems with megalots of lps coral don't like filters. Just live rock and sand, not even a filter sock. A fuge can help; but at 5.00 for 2 pounds of Mrs. Wages' Pickling Lime, this is also one of the most economical systems you can run. If you don't ever let the mg drop, you can run this for months without having to re-set the levels, only adding more ro/di as needed. So just test the mg now and again and you're golden.




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