Opinions on Kalk stirrer and dosing as primary means of pH/Alk/Ca? This vid changed my view of it but want input from others.

[CayeCaulker]

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[Nburg's Reef]

Ok, why do this? By dropping the CO2 levels very low in the tank water and then dosing Kalk you ensure that the hydroxl ion (-OH or base) does not react with the hydrogen ion from the carbonic acid, the normal path for carbonate when using Kalk. Low to no CO2 means low to no carbonic acid. This will beef up the PH because the hydroxl ion is not reacting with the carbonic acid to give you alkalinity i.e. carbonate. This will give you unnaturally high PH, and a lower alkalinity. This lets you move more kalk into the system because you are not running up against accumulated carbonate in the system.

Interesting. Thanks for the write up. Sounds like this system works for him and I hope he has ways to mitigate failure. If I was to go the kalk route, I was going to ditch the CO2 scrubber and just try to maintain a decent pH between 8.2 and 8.4. Would using kalk for primary means of alk/Ca addition to the tank create similar dependencies on all the other parameters?

 

[Yodeling]

The premise, of course, is the assumption that extremely high PH levels (>8.5) are somehow better than normal PH levels (~8.1-8.2). I’ve never seen any evidence or even credible theories to that effect.

In contrast, there are those who struggle to keep normal PH levels and are looking for techniques to get there.

IMHO, we should not conflate the two scenarios

 

[GARRIGA]

I’m smiling when I hit 8. I’ll be more than content if I can keep it 8.2 to 8.4 but if this works and one can replicate then might as well have at it. Only way to verify it provides an advantage is to try it out.

 

[HuduVudu]

I was going to ditch the CO2 scrubber and just try to maintain a decent pH between 8.2 and 8.4. Would using kalk for primary means of alk/Ca addition to the tank create similar dependencies on all the other parameters?

FIrst you need to understand the chemistry that is going on here. When you add calcium hydroxide to water it dissolves (poorly) into Ca+2 and -OH. You do NOT get carbonate from this. The carbonate comes as a second step. When there is CO2 to present over water, and most certianly there will be. Some of that CO2 will be present in the water. Because of chemical affinities some of this dissolved CO2 will get disassociated and become H+ and -2CO3 (bicarbonate) as carbonic acid. This small amount of bicarbonate will always be present in water left in equilibrium with air. It is this bicarbonate that is what is being "added" with the addition of the calcium hydroxide. The chemistry of it is that the -OH (base) combines with the +H (acid) and is nuetrilized into water leaving behind the Ca and CO3. PH plays a role in whether the Ca and CO3 stay in solution or whether they precipitate out. Suffice it to say the higher the PH the higher the precipitation.

Ok, what does that have to do with the price of tea in China? Whelp, if the amount of CO2 is atificially lowered below atmospheric CO2 (~450ppm) then the amount of carbonic acid present in the water is less. There are still metobolic processes at play that add CO2 (respiration). This ensures that the carbonic acid is not zero and must be dealt with chemically or mechanically to keep the carbonic acid low.

The key here is in keeping the carbonic acid out of the system, so that the kalkwasser does not react with it. Because the kalkwasser is simply a base (-OH) and calcium then low carbonic acid means that the base in the kalkwasser is not converted. This is what allows the addition of kalk as a sole source of supplementation. There will be some carbonate (alk) that is converted and this should be more than adequete for skeletal coral growth, but most high demand kalk systems struggle with getting enough calcium. This system allows unnaturally large Ca additions because the PH is pushed high not the alk. Thus keeping the alk in balance with the calcium and allowing the PH to be pushed unnaturally high

TL;DR You can not dose kalk ONLY for high demand systems without using the CO2 scrubbing technique. You will end up with too much alk and not enough Ca.

EDIT: for simplicity and clarity I am using the term alk though I know that hydroxl ions are a part of this equation as base is a buffer.

 

[hans4811]

So curious if the OP @Nburg ever made the switch to just using a kalk stirrer and ditching 2 part dosing ? Would like to do the same as having to mix my alk is becoming a pita….

 

[Nburg's Reef]

So curious if the OP @Nburg ever made the switch to just using a kalk stirrer and ditching 2 part dosing ? Would like to do the same as having to mix my alk is becoming a pita….

Nope, still just chugging along with 2 part and my pH is staying elevated with my scrubber. Everything is doing great so no point in changing now . Mayble I’ll supplement with kale when my demand increases.

 

[BanjoBandito]

I run a kalk stirrer and auto dose it. My ph is usually 8.3 +\-. Kalk is somehow new again. Lol. I think it is fine but it depends on tank size and livestock. I don’t think it can handle a big gallon SPS system. My main concern with my setup is that as stuff starts getting big it won’t be viable for calcium and alk supplementation by itself.

 

[Shooter6]

I dose kalk, 3 part and all for reef on my 400g system

 

[hans4811]

I run a kalk stirrer and auto dose it. My ph is usually 8.3 +\-. Kalk is somehow new again. Lol. I think it is fine but it depends on tank size and livestock. I don’t think it can handle a big gallon SPS system. My main concern with my setup is that as stuff starts getting big it won’t be viable for calcium and alk supplementation by itself.

Great info…just started a new thread on this topic.. https://www.reef2reef.com/threads/c...ace-2-part-dosing-in-a-smaller-system.912482/

Feel free to add any comments..