Kalk overdose, spiked pH 8.8

[David_CO]

When did you last calibrate the pH probe?

2 weeks ago. I also have a handheld Hanna ph probe that’s always within .1 ph. Curious what you think is going on here because I’ve been unable to find many comparable references to me. One thought is my skimmer is definitely undersized from an airflow perspective but I have a really light bioload in this system and didn’t want to strip everything from the water.

 

[WhatCouldGoWrong71]

I wouldn’t freak out. While the swing sucks, I hit 8.7 and 8.8 accidentally a few times as I was dialing in kalk plus the use of sodium hydroxide for an all supplement. I just let it come down naturally and didn’t see any negative impacts up front. This is a mixed reef with heavy LPS. I did switch from hydroxide to BiCarb for the day, so I could still keep my Dkh where it needed to be and also undid my CO2 scrubber. It came down each time relatively quickly. The first time I did this I did use vinegar and a small water change. I felt that dropped it too fast. When I do something dumb and cause a spike, more than likely, I will let it slowly come down on its own. But, I also only brought it down to 8.5 and started the craziness back up. I wish your reeef the best of luck.

 

[Randy Holmes-Farley Verified Community Expert]

2 weeks ago. I also have a handheld Hanna ph probe that’s always within .1 ph. Curious what you think is going on here because I’ve been unable to find many comparable references to me. One thought is my skimmer is definitely undersized from an airflow perspective but I have a really light bioload in this system and didn’t want to strip everything from the water.

I am not aware of anything to worry about with higher pH except excessive abiotic precipitation of calcium carbonate on pumps, hardening sand, etc.

I will note that folks with overdoses where they get a ton of rapid precipitation are usually seeing the pH after the precipitation, and that precipitation itself will lower ph again. So they may have spiked much higher to initially indice the precipitation.

In theory, some photosynthetic organisms that use CO2 (instead of bicarbonate) as their source of CO2 for photosynthesis may start to suffer at elevated pH:

Photosynthesis and the Reef Aquarium, Part I: Carbon Sources by Randy Holmes-Farley - Reefkeeping.com

Relative rates of photosynthesis in seawater (measured by oxygen evolution) at pH 8.7 relative to pH 8.0. A value of 100 means that the rates were the same, and values below 100 indicate less photosynthesis at pH 8.7.​

Species of macroalgae: Relative photosynthesis at pH 8.7 compared to pH 8.1 (as a %):​ Chaetomorpha aerea 75​ Cladophora rupestris 100​ Enteromorpha compressa 67​ Ulva rigida 100​ Codium fragile 76​ Asparagopsis armata 45​ Gelidium pusillum 33​ Gelidium sesquipedale 18​ Gymnogongrus sp. 39​ Osmunda pinnatifida 46​ Porphyra leucosticta 110​ Fucus spiralis 86​ Colpomenia sinuosa 100​ Dictyota dichotoma 53​ Cystoseira tamariscifolia 57​ Padina pavonia 53​

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