Alkalinity/calcium consumption imbalance

[Randy Holmes-Farley Verified Community Expert]

Noted, thank you!

What about for using reef builder for kH if calcium is already too high? Is it better to use kalk?

If calcium is already too high (say, above 550 ppm), then if the goal is to boost pH and alk, sodium hydroxide is the thing to use.

Here a diy two part system using it:

https://www.reef2reef.com/threads/second-new-diy-two-part-recipe-with-higher-ph-boost.357080/

 

[Randy Holmes-Farley Verified Community Expert]

Sorry for the double post, I’m genuinely interested to improve my understanding of this particular issue, as in the past when I tried dosing only kalk on certain systems that I would always overshoot calcium, while struggling to maintain a steady kH. On other systems just using kalk was enough. Is this because of environmental factors external to the tanks as well as the environment/livestock in the tank? If you could shine some light on this for me that would be greatly appreciated! @Randy Holmes-Farley

Kalkwasser will tend to raise calcium over time if used to maintain alkalinity because it is overbalanced in terms of calcium dosing relative to alk.

This is from an older article of mine that explains how I handled it:

Calcium (Ca). In my reef aquarium, I use only Instant Ocean salt and I have not added any additional calcium except as limewater for a number of years (during which time I have continued regular 1% daily water changes). So why is my calcium level (472 mg/L) higher than one would normally expect for Instant Ocean (maybe between 350 and 400 mg/L)? That long term rise in calcium is actually the expected result when using limewater to maintain alkalinity.

Limewater adds calcium and alkalinity in exactly the same proportions as in pure calcium carbonate. So if that is what is used by corals to make skeletons, and what precipitates on pumps and such, then calcium would stay constant.

But both magnesium and strontium get into growing calcium carbonate crystals in place of some of the calcium. A few percent of the calcium is replaced this way. Consequently, since the same amount of alkalinity (the carbonate) is used over time, and somewhat less than the balancing amount of calcium, calcium rises if alkalinity is maintained. I’m happy to see the result match the theory, and the calcium level seems fine to me.

 

[MischiefReef]

If calcium is already too high (say, above 550 ppm), then if the goal is to boost pH and alk, sodium hydroxide is the thing to use.

Here a diy two part system using it:

https://www.reef2reef.com/threads/second-new-diy-two-part-recipe-with-higher-ph-boost.357080/

That is perfect! Thank you!

 

[arking_mark]

I'll just add that I use Kalkwasser and AFR for for Alk/Ca supplementation. Every 6-9 months I need to rebalance by dosing an Alk product for about a week.

 

[MischiefReef]

Kalkwasser will tend to raise calcium over time if used to maintain alkalinity because it is overbalanced in terms of calcium dosing relative to alk.

This is from an older article of mine that explains how I handled it:

Calcium (Ca). In my reef aquarium, I use only Instant Ocean salt and I have not added any additional calcium except as limewater for a number of years (during which time I have continued regular 1% daily water changes). So why is my calcium level (472 mg/L) higher than one would normally expect for Instant Ocean (maybe between 350 and 400 mg/L)? That long term rise in calcium is actually the expected result when using limewater to maintain alkalinity.

Limewater adds calcium and alkalinity in exactly the same proportions as in pure calcium carbonate. So if that is what is used by corals to make skeletons, and what precipitates on pumps and such, then calcium would stay constant.

But both magnesium and strontium get into growing calcium carbonate crystals in place of some of the calcium. A few percent of the calcium is replaced this way. Consequently, since the same amount of alkalinity (the carbonate) is used over time, and somewhat less than the balancing amount of calcium, calcium rises if alkalinity is maintained. I’m happy to see the result match the theory, and the calcium level seems fine to me.

So much more for me to learn on my reefing journey! Thank you for the information!

 

[Randy Holmes-Farley Verified Community Expert]

So much more for me to learn on my reefing journey! Thank you for the information!

You're welcome. That's what makes it fun!

Happy reefing!

 

[rinderb175]

Wondering if anyone can help me make sense of this. My 39 gallon system consumes about 5.74 dKh/week and only 3-4 ppm of calcium (so within the margin or error my Hannah checker). I’ve never had this issue until about a month ago when my weekly testing was showing my Ca was getting much higher than it should. I was hitting 479 ppm using kalkwasser but maintaining an alkalinity level of about 9 dKh. So I switched to dosing just BRS soda ash for a week to bring the Ca level down while maintaining alk levels. It worked and Ca dropped to 439 ppm over a week while alk stayed at 9 dKh. So then I switched back to dosing kalk again to maintain that and sure enough it’s back up to 478 ppm a week later. This is pretty confusing and frustrating because I live in an apartment with 4 other bodies (wife, kid, and 2 dogs) and have had issues keeping pH up, hence why I prefer dosing Kalkwasser. The only explanations I can think of are that either my testing equipment is off or my salt mix is imbalanced. I use IO reef crystals for weekly 10% WC’s. Gonna test my last batch and I’ll post the levels for that in a bit.

All my testing is done with Hannah checkers and here are my tank params

• dKh=9.1
• NH3=17.1
• PH4=0.2
• Ca=478
• Mg=1435
• Salinity=1.026
• Temp 77.5-78.
• Ph=8.1-8.3

I am having a similar issue using reef crystals. I tested my salt mixed water that I will use for my water changes and found out my calcium was at 515ppm @ 1.026 @ 77 degrees.

 

[Rowboman]

I am having a similar issue using reef crystals. I tested my salt mixed water that I will use for my water changes and found out my calcium was at 515ppm @ 1.026 @ 77 degrees.

Woa, that’s high. Not surprisingly high for reef crystals though. I mix a months worth at a time and test the major 3 elements whenever I do a months batch. I’ve tested Ca levels from 370 to 480 ppm, dKh from 7 to 10, and Mg from 1200 to 1400. I’m sure in part this is due to settling, even though I always mix my salt up when I get a new bucket. But sometimes I get consistent results from the salt I used from the top of a brand new bucket all the way to the bottom, only to have my next bucket give me completely different results. Starting to think about switching over to ESV B-ionic after I finish off this bucket of Reef Crystals just because I like that you mix the parts separately. More work but better consistency

 

[Randy Holmes-Farley Verified Community Expert]

I am having a similar issue using reef crystals. I tested my salt mixed water that I will use for my water changes and found out my calcium was at 515ppm @ 1.026 @ 77 degrees.

I don’t know that your measurement is accurate, but if it is, it is fine.