PH chasing mistake…danger of using NaOH to raise pH

kiswanson

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So I made a significant mistake chasing a higher pH and not thinking through what an additive can do. My pH has been on the low side around 7.7-7.9. I added a CO2 scrubber to my skimmer intake and that helped a little, maybe 0.1 on average. I was looking for another option. I would like to add a algae scrubber, but that’s not that easy on a smaller AIO, and the external ones that look good and are reasonably priced are all out of stock (specifically the Tunze).

I happened upon Aquavitro Balance in my LFS - as the bottle says, “balance™ is an optimized blend of sodium and potassium hydroxides with a NSW ratio (27:1)”. Well, I thought, if my pH is low, add some base! I started out with small amounts and there was some bump in pH. I slowly increased the amount I was doing until the pH was up around 8.1-8.2 on average. I thought this was a good solution. I was surprised that the pH dropped quickly if I missed a dose, and I didn’t want to have to keep dosing it long term, but I didn’t think it was too big of a deal if it would help coral growth.

Then I noticed my bubble coral really started retracting and I started getting bleaching/tissue loss on some of my SPS that had previously been doing just fine. At first I thought maybe my nitrates and phos were too high (36 and 0.12), so I started carbon dosing, doing some additional water changes and added some GFO and overtime got my nitrates down to 7-10 and phos down to 0.03-0.06. However those corals weren’t looking better, they were doing worse. I don’t know why I didn’t really pay attention to my alkalinity, but it had been creeping up, but I hadn’t checked it in awhile because I really was only concerned it might get too low and that has not been an issue since I still have small frags and do regular water changes. When I rechecked, the alkalinity was 16.3 (!).

Why so high? I couldn’t figure it out at first. I didn’t think it was the balance, because that wasn’t adding carbonate (I know, I know). My first thought was a problem with my RODI water. I checked that and there was no issue.

Then I listened to the Reef Therapy podcast and they were talking about pH and CO2 in the tank and I finally realized how stupid I had been. Of course there is a constant supply of CO2 to the tank and by adding hydroxide I was driving significant addition of carbonate to the tank. 2 NaOH (s) + CO2 (g) →Na2CO3 (aq) + H2O (l). It was so obvious when I realized it that I obviously felt like an idiot. I stopped dosing and have done a series of large water changes. It’s now down to 11.5.

I ended up losing a number of SPS frags and the bubble coral. Definitely learned some important lessons.
 

chema

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Actually, Randy H-F designed a two-part system based on NaOH aimed to deliver alkalinity to reef systems and also increase pH as a beneficial side effect to those systems which suffer from chronic low pH.

The effect of NaOH on alkalinity is not evident until you realize its interaction with disolved CO2.

I have been using the system for more than three years and I'm very happy with it.
 
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kiswanson

kiswanson

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Actually, Randy H-F designed a two-part system based on NaOH aimed to deliver alkalinity to reef systems and also increase pH as a beneficial side effect to those systems which suffer from chronic low pH.

The effect of NaOH on alkalinity is not evident until you realize its interaction with disolved CO2.

I have been using the system for more than three years and I'm very happy with it.
Interesting…as always more to read and learn
 

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