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pH swings affecting corals
Posted: Wed May 07, 2025 5:26 am
by florian
My tank's pH keeps swinging between 7.8 and 8.4, and my Acropora are looking stressed. Running a 75-gallon with T5 lighting, weekly 10% water changes, and a Reef Octopus skimmer. Anyone dealt with this before?
Re: pH swings affecting corals
Posted: Wed May 07, 2025 5:34 am
by FableKing
pH swings that large can definitely stress SPS. First, check your alkalinity levels—they should be stable around 8–9 dKH. Also, are you dosing anything? A calcium reactor or kalkwasser can help stabilize pH if set up correctly.
Re: pH swings affecting corals
Posted: Wed May 07, 2025 6:27 am
by buddyx
Yep, had the same issue last year. My Torches started retracting, and the Zoas closed up. Turned out my CO2 levels were too high from poor room ventilation. Maybe test your room's air?
Re: pH swings affecting corals
Posted: Wed May 07, 2025 8:25 am
by sealux
I agree with FableKing. Alkalinity is key. My tank runs a Neptune Apex to monitor pH and dose buffers automatically. It's pricey but worth it for SPS.
Re: pH swings affecting corals
Posted: Wed May 07, 2025 8:46 am
by cleverfox
How's your surface agitation? Low flow at the top can cause CO2 buildup, leading to pH drops. Try pointing a powerhead upward or running an air stone at night.
Re: pH swings affecting corals
Posted: Wed May 07, 2025 10:07 am
by florian
Thanks for the tips. I'll test alkalinity tonight and adjust my powerheads. Didn't think about room CO2 being a factor.
Re: pH swings affecting corals
Posted: Wed May 07, 2025 11:18 am
by rivetax
Dude, my pH was all over the place till I started using a fuge with macroalgae. Chaeto sucks up CO2 like crazy, and it's cheap to run. Just a thought.
Re: pH swings affecting corals
Posted: Wed May 07, 2025 12:22 pm
by bronzeo
FableKing wrote: ↑Wed May 07, 2025 5:34 am
pH swings that large can definitely stress SPS. First, check your alkalinity levels—they should be stable around 8–9 dKH. Also, are you dosing anything? A calcium reactor or kalkwasser can help stabilize pH if set up correctly.
Spot on. I'd also recommend a two-part dosing system if you're not ready for a reactor. It's easier to tweak.
Re: pH swings affecting corals
Posted: Wed May 07, 2025 12:56 pm
by FableKing
rivetax wrote: ↑Wed May 07, 2025 11:18 am
Dude, my pH was all over the place till I started using a fuge with macroalgae. Chaeto sucks up CO2 like crazy, and it's cheap to run. Just a thought.
Macroalgae helps, but it's not a standalone fix for large swings. Pair it with proper buffering for best results.
Re: pH swings affecting corals
Posted: Wed May 07, 2025 1:08 pm
by buddyx
Another weird thing—my pH stabilized when I switched salt mixes. Some brands buffer better than others. What salt are you using?