Calfo's Kalk Slurry method

[hazymranch]

Now that my tanks are taking off and with the addition of heaps of frags to them, I have noticed that my calcium needs are outpacing my topoff. So, I have been reading a bit about Anthony Calfo's kalk slurry method. What I gather so far is that I test Ca and then don't dose for 3 days and test Ca again. Divide by 3 and that is my daily Ca requirement. Then,

I am supposed to start with a 1/16 tsp of kalk and mix it in 20 mL of RODI then test the pH too make sure that it doesn't transiently raise the pH by more than 0.2. Then, keep increasing the amount of kalk in the same volume of water in successive doses until I satisfy my Ca requirement or hit the 0.2 pH change threshold.

What I don't get is how to figure out how much Ca is contained in each tsp (or fraction thereof) of kalkwasser. (I am using SeaChem Kalk).

Am I missing anything else?

Is anyone else using this method?

[cookie extreme]

you can not increase your calcium with kalkwasser alone, even when using vinegat in the solution. unless you evaporation is about half your tank volumen. the topup water will only be able to hold so much calcium and that is not enough by a far shot to keep up with demands. it does keep your ph up during the night hours as one benefit if nothing else. thats why some of us use calcium reactors and others 2 part solution's.

[cookie extreme]

a thing to add is that your alk will take a hammering in the process.

[wasp]

How much calcium in a teaspoon?

Kalkawasser is around 55% calcium.

To put it into practicle perspective, a teaspoon, or 3 grams, is as much as you can mix into 2 litres of RODI, to fully saturate it.

Adding this to 100 litres tank water would raise calcium (in theory anyway), by 18 mg/l.

[hazymranch]

you can not increase your calcium with kalkwasser alone, even when using vinegat in the solution. unless you evaporation is about half your tank volumen. the topup water will only be able to hold so much calcium and that is not enough by a far shot to keep up with demands.

I understand that. I used SeaChem Advantage Ca steadily over time on alternate days to Kalk and it has been pretty stable at around 400 to 420. I would like to use Kalk to maintain this level and help balance Alkalinity in the bargain. The low volume of topoff required vs. the higher Ca demand in a tank with so many frags undergoing a fair amount of growth simultaneously pretty much rules out a Kalk drip as a method of maintaining Ca.

However, I have been reading a bit on the slurrly method and it seems that it enables greater solubility % of the solution allowing Ca delivery to exceed the volume limitations of the drip method.

It advises the addition of small doses of a slurry into a highg flow area, causing immediate dispersal and dilution. This is to be repeated until either a pH change of 0.2 (1.5 would be safer) is noted (by electronic measure, ideally) or the calcium level has been raised to target (or at least an adequate but stable).

After sifting through the Wet Web Media FAQ it seems that the Ca part of that equation is meant to be detemined by trial, ie. add 1/4 tsp one night and test the next day to see what the new level is and ratchet in the dose over the next several days. My original question was an attempt to take some of the guesswork out of it.

To put it into practicle perspective, a teaspoon, or 3 grams, is as much as you can mix into 2 litres of RODI, to fully saturate it.

Adding this to 100 litres tank water would raise calcium (in theory anyway), by 18 mg/l.

That's pretty much what I have been using to figure out what my dripping concentration should be, but apparently the slurry method is a more efficient means of delivering Ca via kalk in that there is none of the undissolved precipitate at the bottom of the drip doser because it all gets sent to the tank and dispersed in the water column. If Kalk is 55% Ca (by weight I'm assuming), and if all of it becomes soluble in the tank water then I need to weigh a tsp of kalk and see what 55% of that weight is and do my dilution from there. I was just hoping there was an easier way. :-?

I was hoping that someone had experience with using a slurry instead of a drip and I really don't have the cash to buy Calfo's book to get the step-by-step, as he recommended to almost everyone who asked about it in the FAQ.

Maybe put off thesis writing for a while and DIY a Ca reactor. :roll:

[wasp]

That's pretty much what I have been using to figure out what my dripping concentration should be, but apparently the slurry method is a more efficient means of delivering Ca via kalk in that there is none of the undissolved precipitate at the bottom of the drip doser because it all gets sent to the tank and dispersed in the water column. If Kalk is 55% Ca (by weight I'm assuming), and if all of it becomes soluble in the tank water then I need to weigh a tsp of kalk and see what 55% of that weight is and do my dilution from there. I was just hoping there was an easier way. :-?

It's actually simple enough. If a teaspoon will raise calcium in 100 litres by 18 mg/l, just use that for your calculations. IE if your tank is 300 litres & you want to raise calcium by 18 mg/l, you need 3 teaspoons. If your tank is 300 litres and you wish to raise it by 36 mg/l, use 6 teaspoons.

Couple of things about slurry, watching the pH you obviously have sorted, what I see as a risk, and has happened to me, is if any solid particles go in and are ingested by any corals they can do harm, I have burned white dots onto corals like this. A sump might be the best place to do it & try to get it dissolved before it gets to the main tank.

Dissolving the slurry in vinegar will help with pH issues. Also, kalkawasser dissolved in vinegar, can then be mixed in a jug of tank water instead of fresh water, so in this way you do not have the problem of adding a lot of fresh water to the tank.

[Ira]

I still want to try putting kalk in a fluidized reactor. Just pump a little trickle of water through it so it doesn't disturb the kalk much and any that isn't dissolved should settle before going out of the reactor. Then you have a constant trickle of saturated kalkwater.

That's the idea anyway.

[hazymranch]

It's actually simple enough. If a teaspoon will raise calcium in 100 litres by 18 mg/l, just use that for your calculations. IE if your tank is 300 litres & you want to raise calcium by 18 mg/l, you need 3 teaspoons. If your tank is 300 litres and you wish to raise it by 36 mg/l, use 6 teaspoons.

That's what my original thinking was too, but then I read a bit further and came to realize that those instructions assume the concentration of the supernatant without the precipitate but I am adding the precipitate as well so the working concentration will be higher. I am beginning to realize that I will simply have to ramp up my dose over a few days until I zero in on the right one. I'll use the supernatant concentration dose as a starting place and then ramp up from there.

Dissolving the slurry in vinegar will help with pH issues. Also, kalkawasser dissolved in vinegar, can then be mixed in a jug of tank water instead of fresh water, so in this way you do not have the problem of adding a lot of fresh water to the tank.

I'm glad you said this as this is basically what I do to avoid burning any corals. I mix the kalk in 15mL of vinegar, then mix and top up to 250 mL with RODI. Then the prepared slurry goes into the sump return where the eheim 1262 does a mix on it before shooting it to the tank. It seems to work pretty well but I am becoming a bit concerned about causing ca deposits in my pump. I'll have to keep an eye on it.

[hazymranch]

I still want to try putting kalk in a fluidized reactor. Just pump a little trickle of water through it so it doesn't disturb the kalk much and any that isn't dissolved should settle before going out of the reactor. Then you have a constant trickle of saturated kalkwater.

There are things just like that for sale in the US by companies like Kent Marine. They call them Kalk reactors but basically they are a container with a slow stirring mechanism in the bottom and an outlet somewhere near the top 1/3 of the vessel. From what I have read, they work well enough but are prone to calcification, as you would imagine.