I have a really stupid kalk question.

[Bent]

So here’s the story.

A while back I stopped doing a lot of the stuff I was doing with my tank just so I could kind of see what was going on, what I needed to do, what I didn’t need to do anymore, etc. Sort of backing up to punt in a sense.

So I watched my alk drop slowly over the course of a month, with regular water changes, from 8.48-7.36.

I did some more frequent and larger changes and brought it up to 8.96. This took from feb 27 until March 4. I added 1/2 a cup of kalk on march 5 to the kalk stirrer. On march 7 I had a spike up to 9.28 and on march 11 it went back down to 8.96 and has held exactly at 8.96 ever since.

My question is, when do I refill the stirrer with another 1/2 cup of kalk?

According to the kalk calc on avast, I should have used 3/4 cup every two weeks. I was trying to be conservative so I used 1/2 and I’m sort of glad I did.

Anyway, two weeks is tommorrow and I’m really not sure if I should dump another 1/2 cup in now or if I’m supposed to wait until the alk starts to drop?

Someone please school me.

[bertoni]

One of the disadvantages of a Kalk stirrer is that it's hard to control the dose as precisely, or at least know exactly what the dose is. If you have a conductivity meter that is accurate in the 6-12 mS/cm² zone, you could measure the amount of Kalk in the solution fairly reliably. Failing that, I'd just wait for a bit of a drop in the alkalinity before adding more.

There are a number of processes that affect the saturation of the output. Fresh Kalk powder is mostly calcium hydroxide (or sometimes oxide), and it dissolve readily up to full saturation. That's what happens when people dose a Kalk reservoir. In a reactor, some of the Kalk is converted to calcium carbonate, which might be coating the calcium hydroxide, or otherwise reducing the dissolution limit, possibly by encouraging precipitation. In any case, the output of a Kalk reactor seldom is at full saturation, from what we can tell.

[Bent]

Originally Posted by bertoni

One of the disadvantages of a Kalk stirrer is that it's hard to control the dose as precisely, or at least know exactly what the dose is. If you have a conductivity meter that is accurate in the 6-12 mS/cm² zone, you could measure the amount of Kalk in the solution fairly reliably. Failing that, I'd just wait for a bit of a drop in the alkalinity before adding more.

There are a number of processes that affect the saturation of the output. Fresh Kalk powder is mostly calcium hydroxide (or sometimes oxide), and it dissolve readily up to full saturation. That's what happens when people dose a Kalk reservoir. In a reactor, some of the Kalk is converted to calcium carbonate, which might be coating the calcium hydroxide, or otherwise reducing the dissolution limit, possibly by encouraging precipitation. In any case, the output of a Kalk reactor seldom is at full saturation, from what we can tell.

Thanks, that makes some sense.

So I should wait until I start seeing a drop, then maybe use 1/4 cup instead of half a cup?

[bertoni]

That's probably fine, but you still might see a spike. I don't know how to predict the saturation level. I'd give it a shot, but the tank should be fine, in any case.

[Pife]

Originally Posted by bertoni

One of the disadvantages of a Kalk stirrer is that it's hard to control the dose as precisely, or at least know exactly what the dose is. If you have a conductivity meter that is accurate in the 6-12 mS/cm² zone, you could measure the amount of Kalk in the solution fairly reliably. Failing that, I'd just wait for a bit of a drop in the alkalinity before adding more.

There are a number of processes that affect the saturation of the output. Fresh Kalk powder is mostly calcium hydroxide (or sometimes oxide), and it dissolve readily up to full saturation. That's what happens when people dose a Kalk reservoir. In a reactor, some of the Kalk is converted to calcium carbonate, which might be coating the calcium hydroxide, or otherwise reducing the dissolution limit, possibly by encouraging precipitation. In any case, the output of a Kalk reactor seldom is at full saturation, from what we can tell.

What about the aqua medic stirrer that spins constantly? Does it provide a consistent saturation level?

[bertoni]

I don't think any of them provide a constant saturation level, but I have no true understanding of why.

[Pife]

Thanks

[Greg 45]

While adding kalk is the percentage of alk and calcium at a 50 /50 % . Or is there more of one than the other.

[Bent]

Thanks!

I’ll give it a whirl.

[bertoni]

Originally Posted by Greg 45

While adding kalk is the percentage of alk and calcium at a 50 /50 % . Or is there more of one than the other.

Kalk adds them at the rate of 2.8 dKH per 20 ppm Ca⁺⁺, which is the same ratio as in calcium carbonate.