Is my kalk dosing plan correct?

[Wrasse-cal]

Hi all,

I plan to start dosing kalk to raise my pH--which even with a CO2 scrubber, chateo reactor and outside air stays at 7.95-8.05.

I presently run a Calcium reactor and have an alkatronic monitoring my KH. My KH is fairly stable between 8.50 and 8.60 tested every two hours.

I measured my daily evaporation by measuring the amount of water replaced by my ATO. I found I loose roughly 3500 ml of water per day.

My plan is to dose Kalk from a sealed reservoir. Based on my reading of this article by @Randy Holmes-Farley, there should not be much degradation of the kalkwasser, provided I ensure there are at least some undissolved kalk on the bottom of the reservoir and there is no stirring or aeration. Is this correct?

I estimate that my daily change of KH is 1.08. I estimated this by finding two measurements when my KH measured high, which triggered my CA reactor shutting off. Upon retesting my KH two hours later, I was able to see how much KH was used.

• 8.62-->8.51 = .11
• 8.64-->8.57= .07

.18/2=.09 average change in 2 hours (.045 per hour) x 24 = 1.08.

Based on this calculator, adding 110 ml will raise my KH .045. Therefore, my plan would be to dose 100 ml/hour to start, or 2400 ml per day, which is less than my daily evaporation rate.

Does this make sense? Should I start lower, like at 60 ml per hour?

As to dosing, I plan to use a peristaltic pump to add saturated kakwasser back into the tank. I plan to have the pump turn off if my KH measures above 8.60 as a safety measure.

I'll turn my CA reactor off, during this test. Will I need to dose Mg, and if so, how much? Is there a calculator I can use to identify the balanced Mg dose based on kalk use?

 

[topjimmy]

You can probably make up all of your evaporation with Kalk. But starting where you are should not be an issue. Just keep an eye on ph.

I dose a liter of Kalk a day and just make up for the rest with fresh water and two part for alk/cal.

 

[Breadman03]

I just added a kalk reactor yesterday to help with lower pH, namely about 7.6-7.9 with a long-ago-calibrated Apex pH probe. I don't know how far off the probe has drifted, but it reads low even when calibrated. Consider me as boosting pH to counteract CARX effects.

My display evaporates about 9300 ml/day based on Apex logs. I use a DOS for my ATO set to dose 2,000ml/day unless my low level float is triggered. I set the kalk pump to pump 30 ml every 15 minutes to keep pH impact more stable instead of hitting it with 120 ml hourly. I plan on keeping the CARX running, but will adjust it to meet the balance of demand after kalk contribution.

 

[Wrasse-cal]

You can probably make up all of your evaporation with Kalk. But starting where you are should not be an issue. Just keep an eye on ph.

I dose a liter of Kalk a day and just make up for the rest with fresh water and two part for alk/cal.

Wouldn't that raise my KH based on my estimated daily consumption?

 

[Wrasse-cal]

I just added a kalk reactor yesterday to help with lower pH, namely about 7.6-7.9 with a long-ago-calibrated Apex pH probe. I don't know how far off the probe has drifted, but it reads low even when calibrated. Consider me as boosting pH to counteract CARX effects.

My display evaporates about 9300 ml/day based on Apex logs. I use a DOS for my ATO set to dose 20,000ml/day unless my low level float is triggered. I set the kalk pump to pump 30 ml every 15 minutes to keep pH impact more stable instead of hitting it with 120 ml hourly. I plan on keeping the CARX running, but will adjust it to meet the balance of demand after kalk contribution.

Wait...why are you dosing over 2x your evaporation rate?

 

[dwest]

Hi all,

I plan to start dosing kalk to raise my pH--which even with a CO2 scrubber, chateo reactor and outside air stays at 7.95-8.05.

I presently run a Calcium reactor and have an alkatronic monitoring my KH. My KH is fairly stable between 8.50 and 8.60 tested every two hours.

I measured my daily evaporation by measuring the amount of water replaced by my ATO. I found I loose roughly 3500 ml of water per day.

My plan is to dose Kalk from a sealed reservoir. Based on my reading of this article by @Randy Holmes-Farley, there should not be much degradation of the kalkwasser, provided I ensure there are at least some undissolved kalk on the bottom of the reservoir and there is no stirring or aeration. Is this correct?

I estimate that my daily change of KH is 1.08. I estimated this by finding two measurements when my KH measured high, which triggered my CA reactor shutting off. Upon retesting my KH two hours later, I was able to see how much KH was used.

• 8.62-->8.51 = .11
• 8.64-->8.57= .07

.18/2=.09 average change in 2 hours (.045 per hour) x 24 = 1.08.

Based on this calculator, adding 110 ml will raise my KH .045. Therefore, my plan would be to dose 100 ml/hour to start, or 2400 ml per day, which is less than my daily evaporation rate.

Does this make sense? Should I start lower, like at 60 ml per hour?

As to dosing, I plan to use a peristaltic pump to add saturated kakwasser back into the tank. I plan to have the pump turn off if my KH measures above 8.60 as a safety measure.

I'll turn my CA reactor off, during this test. Will I need to dose Mg, and if so, how much?

I can’t comment on your calculations. However, I would highly recommend an avast kalk stirrer instead of the ato. I ran kalk through my ato for about 20 years and have had the avast k2 stirrer about a year. I find the maintenance is considerably less with the stirrer. Good luck either way.

 

[Breadman03]

Wait...why are you dosing over 2x your evaporation rate?

It was a typo that I just fixed. It should have read 2,000.

 

[Wrasse-cal]

I can’t comment on your calculations. However, I would highly recommend an avast kalk stirrer instead of the ato. I ran kalk through my ato for about 20 years and have had the avast k2 stirrer about a year. I find the maintenance is considerably less with the stirrer. Good luck either way.

I'm not planning on using a stirrer or ATO. Just a reservoir and a peristaltic pump.

 

[Wrasse-cal]

@Randy Holmes-Farley and #reefsquad, would you mind commenting on my math/chemistry? I’d like to make sure I’m not making an error that I will regret...I’ve got a lot of SPS I would hate to nuke.

 

[Brew12]

@Randy Holmes-Farley and #reefsquad, would you mind commenting on my math/chemistry? I’d like to make sure I’m not making an error that I will regret...I’ve got a lot of SPS I would hate to nuke.

What you are doing is exactly what I do other than I do 2-part dosing instead of a calc reactor. I dose 1400mL saturated kalk per day.

I'll check your calculations but I missed it if you posted your total water volume.

 

[Wrasse-cal]

What you are doing is exactly what I do other than I do 2-part dosing instead of a calc reactor. I dose 1400mL saturated kalk per day.

I'll check your calculations but I missed it if you posted your total water volume.

Thanks!

I’m estimating 75 gallons of water in a 100 gallon system.

 

[Brew12]

I’m estimating 75 gallons of water in a 100 gallon system.

Great, let me offer my opinion.

My plan is to dose Kalk from a sealed reservoir. Based on my reading of this article by @Randy Holmes-Farley, there should not be much degradation of the kalkwasser, provided I ensure there are at least some undissolved kalk on the bottom of the reservoir and there is no stirring or aeration. Is this correct?

Yes, this is correct. You may lose a little potency but if you keep the surface of the water calm it will crust over and minimize air exchange.

Does this make sense? Should I start lower, like at 60 ml per hour?

I'll turn my CA reactor off, during this test. Will I need to dose Mg, and if so, how much? Is there a calculator I can use to identify the balanced Mg dose based on kalk use?

If your goal is to turn off the calcium reactor until your demand exceeds what you can add in kalkwasser I think it makes sense. The numbers I ran show that it may be a hair low but imo it is better to be a bit low than high. If you go this route I would do it on a day that I can test often. The 2 hour consumption test may not be a long enough sample when you take into consideration the precision of the alkalinity measurements.

This does have some drawbacks other than just Mg. The Calc reactor also replaces other trace elements. I know some people like calcium reactors to help minimize needed water changes. If you aren't doing regular ones you will need a plan to replace more than just Mg. There is not a calculator for Mg usage. Calcium and Alk work hand in hand because they are used in a known proportion. Some corals can take up 5 times or more Mg than others so Mg usage will vary based on the types of coral in the tank.

 

[Wrasse-cal]

Thanks, @Brew12

 

[rkpetersen]

Great, let me offer my opinion.

Yes, this is correct. You may lose a little potency but if you keep the surface of the water calm it will crust over and minimize air exchange.



If your goal is to turn off the calcium reactor until your demand exceeds what you can add in kalkwasser I think it makes sense. The numbers I ran show that it may be a hair low but imo it is better to be a bit low than high. If you go this route I would do it on a day that I can test often. The 2 hour consumption test may not be a long enough sample when you take into consideration the precision of the alkalinity measurements.

This does have some drawbacks other than just Mg. The Calc reactor also replaces other trace elements. I know some people like calcium reactors to help minimize needed water changes. If you aren't doing regular ones you will need a plan to replace more than just Mg. There is not a calculator for Mg usage. Calcium and Alk work hand in hand because they are used in a known proportion. Some corals can take up 5 times or more Mg than others so Mg usage will vary based on the types of coral in the tank.

Here I was putting together a reply, and Brew12 said everything I was going to say already.
For 75 gallons, a 24 hour administration of 1.08 dKH would be 2690 ml kalkwasser. So you should be fine starting at 100 ml/hour and possibly working up from there.
Agree that I would definitely do some longer interval dKH drop measurements, at least 8 hours.
I understand that you have a working plan, but I'd add my voice to those who suggest using a reactor over a simple container or ato. Easier and neater.

 

[Wrasse-cal]

Here I was putting together a reply, and Brew12 said everything I was going to say already.
For 75 gallons, a 24 hour administration of 1.08 dKH would be 2690 ml kalkwasser. So you should be fine starting at 100 ml/hour and possibly working up from there.
Agree that I would definitely do some longer interval dKH drop measurements, at least 8 hours.
I understand that you have a working plan, but I'd add my voice to those who suggest using a reactor over a simple container or ato. Easier and neater.

Thanks for the reply.

As to reactor/kalk reservoir, I'm struggling to understand the benefit of a reactor. Basically, if I understand correctly, I can just top off the kalk reservoir with RODI and as long as there is still a slurry in the base, I'm good to go.

If I were going to get a reactor, I'd get the GEO reactor. The only benefit I see is I'd only have to top off my ATO vs my ATO and Kalk reservoir. The downside would be the stirrer pump would run every X hours. Since I plan on continuous dosing via a peristaltic pump, I'd have to turn on and off my pump regularly to let the solids settle, right? That sounds more complicated to me. Am I missing something?

 

[dwest]

Thanks for the reply.

As to reactor/kalk reservoir, I'm struggling to understand the benefit of a reactor. Basically, if I understand correctly, I can just top off the kalk reservoir with RODI and as long as there is still a slurry in the base, I'm good to go.

If I were going to get a reactor, I'd get the GEO reactor. The only benefit I see is I'd only have to top off my ATO vs my ATO and Kalk reservoir. The downside would be the stirrer pump would run every X hours. Since I plan on continuous dosing via a peristaltic pump, I'd have to turn on and off my pump regularly to let the solids settle, right? That sounds more complicated to me. Am I missing something?

I “continuously dose” into my kalk stirrer via my liter meter 3 (I think it runs about every 10 minutes). I think it’s similar to what you are contemplating.

The advantage for me is maintenance. If you have a kalk reservoir (mine old one was big....about 20 gallons), you will need to dump out the slurry that remains in the bottom every now and then. You will eventually get some precipitated calcium carbonate and also some heavy metal carbonates in the bottom. The pump also pumps kalk, which does precipitate in the lines some and is often tough on the pump.

With my stirrer, my pump pumps RODI water to the stirrer. The saturated kalk drips out of the stirrer into my sump. So the maintence I do is dump out the sludge in the bottom of the stirrer every 6 months or so. My kalk stirrer is much smaller than my old kalk reservoir, so that job is much easier.

Bottom line is what you are discussing will work great. IME the stirrer is just easier. I also think that either way, you should do the dosing like you had planned vs. ato.

 

[rkpetersen]

Thanks for the reply.

As to reactor/kalk reservoir, I'm struggling to understand the benefit of a reactor. Basically, if I understand correctly, I can just top off the kalk reservoir with RODI and as long as there is still a slurry in the base, I'm good to go.

If I were going to get a reactor, I'd get the GEO reactor. The only benefit I see is I'd only have to top off my ATO vs my ATO and Kalk reservoir. The downside would be the stirrer pump would run every X hours. Since I plan on continuous dosing via a peristaltic pump, I'd have to turn on and off my pump regularly to let the solids settle, right? That sounds more complicated to me. Am I missing something?

You can't really just top off a kalk reservoir and have it function consistently. For that to happen, the solution inside has to stay saturated at all times. Calcium hydroxide isn't very soluble in water, so you have to top off and then mix thoroughly every time.

The residue at the bottom will be mostly undissolved calcium hydroxide but will over time accumulate some calcium carbonate as well. Both of these can be rough on pumps and tubing, so it's safer imo to have the pump in a different container like a pure water ato reservoir.

Although you can also just keep the pump off the bottom of the container as well.

You're right it wouldn't be ideal with continuous kalk dosing, but you can set the stirrer to run whenever you want. Doesn't have to run for long, just a few minutes, and all the precipitate will have pretty much settled within 30 minutes or so.

 

[Brew12]

You can't really just top off a kalk reservoir and have it function consistently. For that to happen, the solution inside has to stay saturated at all times. Calcium hydroxide isn't very soluble in water, so you have to top off and then mix thoroughly every time.

Just to be clear, you only need to mix it thoroughly every time you mix up a new batch. Once the batch is mixed, its pretty much good to go until you need to refill.

Randy has two great articles on kalkwasser.
http://reefkeeping.com/issues/2003-05/rhf/feature/index.htm
http://reefkeeping.com/issues/2005-01/rhf/index.php#11

 

[Retro Reefer]

Agree with Brew12 I only mix once and store Kalkwasser for 2-3 weeks at a time, my vessel is air tight and I draw from mid level to refill my Kalk dosing container as needed.