Kalkwasser ph vs alk and ca

[Acroporaaddict]

Im using a kalk stirrer, (3500ml between 2000 and 0600) when i top off with fresh powder or clean and refill my ph is elevated for a few days. Slowly, my ph drops while my dkh and ca remain stable. Does kalwasser lose it ph raising benefits and still maintain the same dkh and ca addition or should it be a linear decrease?

 

[bioforge]

Im using a kalk stirrer, (3500ml between 2000 and 0600) when i top off with fresh powder or clean and refill my ph is elevated for a few days. Slowly, my ph drops while my dkh and ca remain stable. Does kalwasser lose it ph raising benefits and still maintain the same dkh and ca addition or should it be a linear decrease?

pretty sure this isnt a straight line, more like a step down. co2 in the air reacts with the kalk mix and forms a crust on top pretty quick. right when you mix a fresh batch theres no crust yet so those first doses are full strength, thats your ph bump. after a few days the crust builds up and kind of seals the rest of it off from more co2, so it settles into a lower steady state and the ph eases back down.


dkh and ca still test stable because ph is a log scale, way more sensitive to small changes than a titration based alk/ca test picks up. a swing that moves ph noticeably can be well within the margin of error on your alk or ca kit.


if you want something more consistent punch the whole cycle, keep it sealed up tight between doses, thats really the main lever you have

 

[Randy Holmes-Farley Verified Community Expert]

Im using a kalk stirrer, (3500ml between 2000 and 0600) when i top off with fresh powder or clean and refill my ph is elevated for a few days. Slowly, my ph drops while my dkh and ca remain stable. Does kalwasser lose it ph raising benefits and still maintain the same dkh and ca addition or should it be a linear decrease?

It loses potency for all effects as less and less dissolves usefully into the reactor. I expect you just do not notice the alk effect as rapidly and the calcium moves much more slowly.

pH is complicated by aeration and the fact that it is a log scale, so it’s not really possible to characterize the effect against the alk effect.

In a perfectly aerated tank, the pH rise would be very small if noticeable at all.

 

[bioforge]

Hmmm that makes sense. I was looking at it from the observation that pH changed much more noticeably than alk and calcium. You’re saying the potency loss affects all three, but pH is the hardest to interpret because it’s also strongly influenced by aeration and CO₂. Thanks for the clarification Randy

 

[Randy Holmes-Farley Verified Community Expert]

Hmmm that makes sense. I was looking at it from the observation that pH changed much more noticeably than alk and calcium. You’re saying the potency loss affects all three, but pH is the hardest to interpret because it’s also strongly influenced by aeration and CO₂. Thanks for the clarification Randy

Yes.

Happy reefing!

 

[Acroporaaddict]

if you want something more consistent punch the whole cycle, keep it sealed up tight between doses, thats really the main lever you have

Punch the whole cycle? Im not following

 

[Acroporaaddict]

It loses potency for all effects as less and less dissolves usefully into the reactor. I expect you just do not notice the alk effect as rapidly and the calcium moves much more slowly.

pH is complicated by aeration and the fact that it is a log scale, so it’s not really possible to characterize the effect against the alk effect.

In a perfectly aerated tank, the pH rise would be very small if noticeable at all.

My concern is its getting hot (southern CA, tank is near a west facing sliding glass door) id like to close the door and run the ac but im worried about the night time ph drop. Nothing in the tanks environment changes. Same surface agitation by powerheads, same photoperiod, sliding glass door 5 feet away from the tank is open 24/7. Only variable that im aware of is the the time since kalkwasser reactor was topped off or fully cleaned and refilled. After refill or cleaning night time low ph is 8.3 and stable for 2-3 days. After that, ph drops about .05 each night. Once the night time ph drops to 8.0 i refill or clean and fill the reactor. Tank has a trident on it testing 8x per day and i have been verifying with salifert and hanna 2- 3x per week. Ph appears to be dropping while carbonate and calcium remains stable. As i mentioned above, im dosing 3500ml of kalwasser each night and add 1/4 cup of new kalk weekly. I feel like im going through alot of kalk for a very short lived ph increase. Thats why im questioning the linear degradation. Would sodium hydroxide and calcium chloride swapped out for current calcium hydroxide consumption levels provide a more consistent ph level?

 

[PPBlimpy]

I personally have never used kalk to chase PH. I feel that it can be dangerous but see a lot of people do that.
Kalk is easy and cheap to keep alm/cal where I want it. The PH boost was a benefit. If my tanks stay above 8.0 I am more than happy. Generally dosed 2:1 night to day to keep ph more stable and my ATO from kicking in often.

Instead of the door open can you run your skimmer air inlet outside? That made a big difference in my tanks

 

[Peer.Boerner]

I personally have never used kalk to chase PH. I feel that it can be dangerous but see a lot of people do that.
Kalk is easy and cheap to keep alm/cal where I want it. The PH boost was a benefit. If my tanks stay above 8.0 I am more than happy. Generally dosed 2:1 night to day to keep ph more stable and my ATO from kicking in often.

Instead of the door open can you run your skimmer air inlet outside? That made a big difference in my tanks

I do this and use a co2 scrubber and it works great.

 

[Randy Holmes-Farley Verified Community Expert]

Thats why im questioning the linear degradation. Would sodium hydroxide and calcium chloride swapped out for current calcium hydroxide consumption levels provide a more consistent ph level?

FWIW, I have never have claimed reactors are a good way to deliver kalk, nor that the effluent is linear in degradation over time. Reactors often produce less than saturated kalk.

Are you tracking alk? I also do not recommend dosing any alk supplement based on pH only.

 

[helmsreef]

I always run Kalk 24/7 at max evap rate and I do see a noticeable difference in PH while doing so. I also have a friend who only doses full evap amount at night and his PH never really jumps that much higher. I also use a sealed reactor and not a stirrer and I keep all my doors and windows closed with 4 family members and 3 large dogs and I typically wont see ph drop below 8.2 and a max of about 8.5. I don't use it for primary a PH booster but as an additional way of adding alk and cal as the calcium reactor does most of the lifting. I base everything off of my ALK though and the PH boost is just a benefit.