Kalk stirrer for pH boosting only

[Reefcowboy]

Have an sps 150 gal that has been doing great. Only issue is pH hovers between 7.7-8.1.

My alk and Ca levels are on point through 2 part dosing.
I got a kalk stirrer and want to drip it through a dosing pump to keep pH between 8.2-8.4.

So here are my questions:

1- the volume of the stirrer is 1 gallon. How many tsp to saturate it? I followed the instructions on the kalk bag of 2 tsp and there is no deposit at the bottom of the reactor body.
I havent dosed any yet. What is the max saturation dose for 1gallon?

2- I was planning on dosing according to pH vs evaporation(ATO) in order to be more precise. I have an Apex and planned on slowly ramping pH over the next few days and drip when pH dropped to keep it at target levels. I also planned to set some safeties to avoid excessive drip.
Is my thinking wrong?

 

[RamsReef]

Good luck, if everything is stable I wouldnt medd with it.

 

[Mrx7899]

I have mine hooked up to my ato and put a cup of kalk in the stirrer every 2 weeks. The table spoon per gallon doesn't apply to a stirrer. Here is a chart that shows how much to put in.

 

[Reefcowboy]

I have mine hooked up to my ato and put a cup of kalk in the stirrer every 2 weeks. The table spoon per gallon doesn't apply to a stirrer. Here is a chart that shows how much to put in.

Thank you. At this measurement, how much deposit do you notice at the bottom of the stirrer? When it gets close to refill(2 weeks) do you notice sludge or does it get reduced/disolved with water dilution through that time? I wonder if adding a bit extra would have any impact as long as the deposit at the bottom doesnt keep increasing too much?

 

[dwest]

Thank you. At this measurement, how much deposit do you notice at the bottom of the stirrer? When it gets close to refill(2 weeks) do you notice sludge or does it get reduced/disolved with water dilution through that time? I wonder if adding a bit extra would have any impact as long as the deposit at the bottom doesnt keep increasing too much?

A bit extra is fine and is what I do. In fact, I add enough kalk for a couple of months of use. When the layer on the bottom gets down to 1/4 inch or so, I add in more. I keep a ph probe in my stirrer and can keep my kalk solution saturated this way using my spectrapure liter meter 3.

 

[Reefcowboy]

A bit extra is fine and is what I do. In fact, I add enough kalk for a couple of months of use. When the layer on the bottom gets down to 1/4 inch or so, I add in more. I keep a ph probe in my stirrer and can keep my kalk solution saturated this way using my spectrapure liter meter 3.

Thank you. What is the usual pH reading in the stirrer? I have my pH probe running for less than a year in my sump,just ordered some solution to calibrate it soon as I want it to be as accurate as possible with the use of kalk.

How often should I calibrate the probe? How about replacement time?

 

[Mrx7899]

Thank you. At this measurement, how much deposit do you notice at the bottom of the stirrer? When it gets close to refill(2 weeks) do you notice sludge or does it get reduced/disolved with water dilution through that time? I wonder if adding a bit extra would have any impact as long as the deposit at the bottom doesnt keep increasing too much?

There is about an inch and a half of stuff on the bottom. I usually empty it out once a month or so and clean it. I dont have a ph probe in mine but it think the ph should be around 12.

 

[dwest]

Thank you. What is the usual pH reading in the stirrer? I have my pH probe running for less than a year in my sump,just ordered some solution to calibrate it soon as I want it to be as accurate as possible with the use of kalk.

How often should I calibrate the probe? How about replacement time?

Well, I’ve used kalk for about 20 years or so, but only have used a stirrer for about 8 months. Mine is an avast k2 and I think it’s great. I’ve been experimenting a lot with it for sure. I put my pH probe in the stirrer just to make sure my solution is saturated when the kalk is fresh and after it has been in the stirrer a while.

So to answer your question, the pH I measure in the stirrer is 12.3. The pH will depend on temperature, and is supposed to be 12.4 at 25c. But, since I calibrate at 4 and 10, I don’t expect my number to be accurate, but was looking for the pH to not change inside the stirrer as the kalk ages.

What I have learned is that my solution is saturated as long as I see solids in the bottom. As long as I dump the solids every 6 months or so everything is good. In fact I probably won’t use the pH probe for much longer. But I think you should at first because it’s cool.

 

[Randy Holmes-Farley]

FWIW, you are supposed to have substantial undissolved calcium hydroxide on the bottom of a stirrer. You do not add new material every time a gallon passes through. That said, the effluent from many such reactors is not saturated, and folks are often surprised when they actually test it and find it isn't (by, say conductivity, saturation is a bit above 10 mS/cm).

You can also switch to a very high pH two part (DIY), if you want the same effect using just a two part.

 

[dwest]

FWIW, you are supposed to have substantial undissolved calcium hydroxide on the bottom of a stirrer. You do not add new material every time a gallon passes through. That said, the effluent from many such reactors is not saturated, and folks are often surprised when they actually test it and find it isn't (by, say conductivity, saturation is a bit above 10 mS/cm).

You can also switch to a very high pH two part (DIY), if you want the same effect using just a two part.

Why do you prefer conductivity rather than pH to determine saturation of kalk?

 

[Randy Holmes-Farley]

Why do you prefer conductivity rather than pH to determine saturation of kalk?

pH is very crude in this regard, and the pH will be very high even when the limewater is quite weak.

Saturated limewater at 25 deg C has a pH about 12.54.

If the limewater is only half saturated, the pH will still be above 12, around 12.24. pH 12.3 looks strong, but is not near saturation.

So unless you can calibrate and measure very carefully, it is not especially precise.

If I were to do it, I'd measure the pH of totally saturated limewater (say, put 2 tablespoons in a cup of RO/DI and mix. Then compare that value you get there to the value of the effluent. A drop of 0.3 pH units is about 50% drop in potency.

I show how to measure the potency by conductivity here:
http://reefkeeping.com/issues/2003-05/rhf/feature/index.htm

 

[dwest]

pH is very crude in this regard, and the pH will be very high even when the limewater is quite weak.

Saturated limewater at 25 deg C has a pH about 12.54.

If the limewater is only half saturated, the pH will still be above 12, around 12.24. pH 12.3 looks strong, but is not near saturation.

So unless you can calibrate and measure very carefully, it is not especially precise.

If I were to do it, I'd measure the pH of totally saturated limewater (say, put 2 tablespoons in a cup of RO/DI and mix. Then compare that value you get there to the value of the effluent. A drop of 0.3 pH units is about 50% drop in potency.

I show how to measure the potency by conductivity here:
http://reefkeeping.com/issues/2003-05/rhf/feature/index.htm

Thank you. I will check my effluent vs. known saturated kalk like you mention.

I have read that before. Great article!

 

[Randy Holmes-Farley]

Thanks.

Happy Reefing [emoji3]