High pH - good for corals, bad for fish?

[Randy Holmes-Farley Verified Community Expert]

My aquarium regularly peaked at pH 8.55 for a long time and I saw no apparent issues with fish or any other organism that I could attribute to pH.

 

[Dom]

Yeah I’m not exactly sure… that’s why I was asking Jay if he had any intel.. I know I’ve read it, in a few places. I did a quick google search and aquaforest had this to say.. if it’s true or not I have no clue. But I have heard it a few times or better yet I should say read it! They don’t clarify what’s high thou lol..

This is interesting. I'm curious to hear what Jay has to say on this.

 

[Randy Holmes-Farley Verified Community Expert]

This is interesting. I'm curious to hear what Jay has to say on this.

https://www.reef2reef.com/threads/high-ph-good-for-corals-bad-for-fish.1060282/#post-12630473

 

[ISpeakForTheSeas]

High pH reportedly can cause issues with fish and inverts (not necessarily killing them, but possibly harming them, causing long-term issues, and/or shortening their lifespans), but there are very few studies I can find on it. It does seem that high pH may be lethal to sensitive inverts like pods.

Unfortunately, what level is considered high seems to vary by a number of factors (species, temperature, salinity, etc.), so that muddies the water a bit here.

Some articles for those interested:
https://www.researchgate.net/public...ile_turbot_Scophthalmus_maximus_Linnaeus_1758https://setac.onlinelibrary.wiley.com/doi/full/10.1002/etc.5282https://www.sciencedirect.com/science/article/pii/S2352513415300107https://academic.oup.com/plankt/article/39/6/984/3869501https://link.springer.com/article/10.1007/s00343-020-0063-0https://www.biorxiv.org/content/10.1101/2024.01.05.574400v1.full(This last one is interesting, as it shows that ash had an unexpected physiological impact on the fish as well that wasn't explained by the pH).

 

[Randy Holmes-Farley Verified Community Expert]

Some of these effects are in fresh water and happen at pH values unattainable in a reef tank.

 

[ISpeakForTheSeas]

Some of these effects are in fresh water and happen at pH values unattainable in a reef tank.

Yeah, there were only a few dealing with marine conditions and fewer still dealing with fish - I mostly listed the freshwater ones because I found them interesting and figured others might too (and I tend to get sidetracked a bit when learning about new topics - sorry).

 

[GARRIGA]

Apparently pH 9 made it to FB and being discussed here. Lots of good info on pH and how to avoid issues by learning of others mistakes. Interesting adaption of calcium co2 feed to quickly solve higher than wanted pH from Kalk mishap. Making me consider having a co2 cylinder on standby should that potential Kalk slurry disaster occur.

 

[Garf]

I expect the water would be very cloudy at pH 9. Mine clouds approaching 8.6, so added a CO2 source to limit it at 8.4. I expect it would have just been simpler to lower how much kalk I add however, lol.

 

[GARRIGA]

I expect the water would be very cloudy at pH 9. Mine clouds approaching 8.6, so added a CO2 source to limit it at 8.4. I expect it would have just been simpler to lower how much kalk I add however, lol.

Obviously but often I do what I tried avoiding :rolling-on-the-floor-laughing:

 

[Ziggy17]

My PH swings from 8.2 in the morning to 8.5 by end of the day, could shade a little over 8.5 to 8.55. I don’t have any precipitation and calcium appears stable. I’d like it to stay in the 8.3-8.4 range but it just does what it does so I stopped fighting it. And that’s with Alk at 8.3 using DIY sodium bicarbonate liquid.