DKh of kalkwasser?

[NEFFx]

Howdy, was curious on the efficacy of my kalkwasser product since my dkh has dropped from 7.3 to 5.8 since i switched brands from brightwell to seachem. I dose 2g a day.

the only other thing that changed was the addition of a CO2 scrubber on the skimmer. Which is annoying because that could also dramatically increase the uptake and lead to the readings, but I adjusted the calcium reactor from 50mlmin to 80ml/min when I added that. Now it’s at 150ml min because being at 130mlmin for 10 hours didn’t impact the kh.

It’s a 210g with light to moderate sps stocking.

so I’m trying to figure rest the Kalk on its own. The two things I can imagine to test are ph and dkh. I have a probe and Hanna test for each. Thoughts?

 

[Randy Holmes-Farley]

Howdy, was curious on the efficacy of my kalkwasser product since my dkh has dropped from 7.3 to 5.8 since i switched brands from brightwell to seachem. I dose 2g a day.

the only other thing that changed was the addition of a CO2 scrubber on the skimmer. Which is annoying because that could also dramatically increase the uptake and lead to the readings, but I adjusted the calcium reactor from 50mlmin to 80ml/min when I added that. Now it’s at 150ml min because being at 130mlmin for 10 hours didn’t impact the kh.

It’s a 210g with light to moderate sps stocking.

so I’m trying to figure rest the Kalk on its own. The two things I can imagine to test are ph and dkh. I have a probe and Hanna test for each. Thoughts?

The best way to measure the saturation of kalkwasser is by conductivity. Saturation is about 10.3 mS/cm at 25 deg C. Saturation is essentially linear with conductivity.

pH can be used crudely. To do so, make a guaranteed saturated solution by mixing a couple of tablespoons in a cup of RO/DI, and measure the pH. It should be around 12.5, but the exact value isn't critical. Then measure the pH of the kalkwasser you are interested in. The degress of saturation can be roughly calculated from the ph difference between these two solutions. A difference of 1 pH unit menas it is 10% saturated, a difference of 0.3 units means it is 50% saturated, and a difference of 0.1 pH unit means it is 80% saturated.

FWIW, the potency of saturated kalkwasser at 25 deg C is 114 dKH and the calcium level is 808 ppm. That said, undissolved particles in it will give a false high reading of either of these as they dissolve in the test.

 

[NEFFx]

Thanks Randy. So I won’t be able to test the Kalk potency unless I dissolve it 10/1 in a hanna test kit with tank saltwater (an order of magnitude less shouldn’t have an impact as it should read around 17-20 dkh). It’s 4.5 cups of Kalk in a reactor. I’m curious if it’s some other solution.

I cleaned the manifold on my trident so hopefully that’ll work and I can view trends again.

 

[Randy Holmes-Farley]

Thanks Randy. So I won’t be able to test the Kalk potency unless I dissolve it 10/1 in a hanna test kit with tank saltwater (an order of magnitude less shouldn’t have an impact as it should read around 17-20 dkh). It’s 4.5 cups of Kalk in a reactor. I’m curious if it’s some other solution.

I cleaned the manifold on my trident so hopefully that’ll work and I can view trends again.

Putting more than a little in seawater will make a mess as it causes precipitation of calcium carbonate and magnesium hydroxide.

 

[NEFFx]

Putting more than a little in seawater will make a mess as it causes precipitation of calcium carbonate and magnesium hydroxide.

Well I meant the dissolved saturated Kalk solution. I just want a test to make sure the product I am using is adequate.

 

[Randy Holmes-Farley]

Well I meant the dissolved saturated Kalk solution. I just want a test to make sure the product I am using is adequate.

"So I won’t be able to test the Kalk potency unless I dissolve it 10/1 in a hanna test kit with tank saltwater (an order of magnitude less shouldn’t have an impact as it should read around 17-20 dkh)"

I meant the dissolved solution as well. If you do as you suggest in the sentence above, mixing the solution into seawater, it will be a mess of preciptiated material. Even adding 2 dKh instantly to seawater risks precipitation.

 

[NEFFx]

So, I tested the Kalk solution with the apex probe. This about 12.1. im assuming that the Kalk is acceptable and not the cause of my drop in KH. that’s 6.5L a day.
I used new Reagent on the kh hanna. Both tested at 6dkh.
I increased the calcium reactor to 180ml/min. Which is 110mil/min more than before I added the CO2 scrubber. That’s at 6.4 Ph in the CaRx.
I cleaned the trident since I guess this mornings cleaning of the lines didn’t hold up.
that said I don’t have another KH test to check the Hanna.
And my PH probe is taking a while to come back down to 8.3 where it should be and is at 8.5, so I may need a calibration or maybe just replace it with the new one I have.

seems strange this is near the previous SPS tank which had at least double the sps coral and similar setup including the co2 scrubber but was dosing 240mil/min and that was running at 8.5-9dkh. And I can’t keep this KH up over 6.

 

[Randy Holmes-Farley]

So, I tested the Kalk solution with the apex probe. This about 12.1. im assuming that the Kalk is acceptable and not the cause of my drop in KH. that’s 6.5L a day.

Just to be clear, it's very hard to judge potency by a single pH measurement alone (due to inaccuracy at high pH), but if exactly ac curate, that kalkwasser less than 50% potent.

 

[NEFFx]

Just to be clear, it's very hard to judge potency by a single pH measurement alone (due to inaccuracy at high pH), but if exactly ac curate, that kalkwasser less than 50% potent.

Yea, but I didn’t let the probe sit there for more than 5 min. It would probably slowly tend to 12.5. At 4.5 cups of Kalk in 2g of water I’m imagine it must be saturated.

 

[Randy Holmes-Farley]

Yea, but I didn’t let the probe sit there for more than 5 min. It would probably slowly tend to 12.5. At 4.5 cups of Kalk in 2g of water I’m imagine it must be saturated.

That is not a correct assumption in an operating kalk reactor where dissolution is often demonstrable not complete, but it certainly would be true in a thoroughly mixed suspension.