Alkalinity Too High? How to Adjust without lowering PH?

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jbilliel

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I have a 5 month old tank that is always running on the low side of the PH scale (7.8-8.0). The only way I have been able to get this up is with Kalkwasser in my ATO, but doing this is putting my dKH up in the 11's. I have a simple softie tank so no real demand for Calcium, Magnesium, etc. I am using Red Sea Coral Pro salt and all of the parameters look good otherwise. Any thoughts on how to get out of this? Is 11+ ok to keep the tank at? I lost some softies recently and was assuming that this was part of the problem.
 
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Dfwminis

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This sounds like if you lower it, it’s just gonna raise back up with kalk giving you the run around. Stable 7.8-8ph is fine so might be better off not using kalk and not have to worry about raising alk too high.
 

Randy Holmes-Farley

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removing CO2 and allowing alk to drop on its own is really the only way.

Fresher air (from outside or a scrubber) aerating the water is the best way to remove CO2.
 
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Randy Holmes-Farley

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Thanks for the help guys. I just purchased a CO2 scrubber to help. I am excited to see if this helps stabilize the ph in the tank as I am tired of chasing it around. lol
It will raise pH, Stabilization of pH comes mostly from the amount of aeration at any pH, not the CO2 level in the aeration air.
 

SMB

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Red Sea Coral Pro mixed with a salinity of 35ppm has a dkh ~11.5 so if you are doing water changes you will be fighting yourself.
I use the same salt, run a dkh of 11.5 which keeps the pH at 8.1-8.2. Weekly 15-20% WC and dosing alk. Doesn't seem to affect my mixed reef for the last 18 months.
The tank is in the basement and I did try running my PS with an airline to the outside but it had no effect on the pH.
Not sure if it is worth the hassle of a C02 scrubber.
 

Billldg

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@Randy Holmes-Farley beat me to it, but I was also going to suggest a C02 scrubber. I use one with great effect. Just make sure you keep putting in a couple ml's of water in the scrubber to keep it moist. I add 30 ml, or 2 table spoons of water daily to keep the media moist.
 

Jacob Fawley

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It will raise pH, Stabilization of pH comes mostly from the amount of aeration at any pH, not the CO2 level in the aeration air.

Does the Kalkwasser itself actually raise Kh? That’s kinda strange to me because it contains no carbonate or bicarbonate. I have heard that Red Sea Coral Pro can give extremely high levels though.
 

Randy Holmes-Farley

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Does the Kalkwasser itself actually raise Kh? That’s kinda strange to me because it contains no carbonate or bicarbonate. I have heard that Red Sea Coral Pro can give extremely high levels though.
Complicated question, but definitely yes.

Even if it all stayed as hydroxide (it doesn't) it would count toward total alkalinity and be measured by a kit. Hydroxide, carbonate, and bicarbonate are only some of the things that get counted:

This has details:


TA = [HCO3–] + 2[CO3—] + [B(OH)4–] + [OH–] + [Si(OH)3O–] + [MgOH+] + [HPO4—] + 2[PO4—] – [H+]
 

Randy Holmes-Farley

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That said, the reason hydroxide is useful for us with respect to corals is that it combines with CO2 and bicarbonate and in the tank system:

OH- + CO2 --> HCO3-

OH- + HCO3- --> CO3-- + H2O

SO it increases hydroxide, carbonate, and bicarbonate when added.
 

blasterman

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Just cut the amount of kalk you use by half. In the meantime cut the kalk off entirely until alk lowers a bit.

This is a common problem with high ATO tanks with low alk usage. After awhile your alk increases from adding kalk with nothing to consume it.
 

Jeff Cahill

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I have a 5 month old tank that is always running on the low side of the PH scale (7.8-8.0). The only way I have been able to get this up is with Kalkwasser in my ATO, but doing this is putting my dKH up in the 11's. I have a simple softie tank so no real demand for Calcium, Magnesium, etc. I am using Red Sea Coral Pro salt and all of the parameters look good otherwise. Any thoughts on how to get out of this? Is 11+ ok to keep the tank at? I lost some softies recently and was assuming that this was part of the problem.
Change you salt coral pro has elevated dkh
 
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jbilliel

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If I stop adding Kalk then the PH drops down too low. Hopefully the CO2 scrubber will help with the PH and then I can stop using the Kalk.
 
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jbilliel

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I am happy to report that within 24 hours, the CO2 scrubber already brought the PH up to 8.3 from 7.8/7.9. The overnight low only dipped to 8.13. Now I can stop the Kalk and truly monitor the coral nutrient usage and adjust from there. Thank you everyone for the insight!
 
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