Ideal pH for coral growth

LPS, SPS and all coral chat
stevana
Posts: 8
Joined: Thu Oct 10, 2024 5:34 pm

Ideal pH for coral growth

Post by stevana »

My corals aren't growing like they used to. I've been keeping my pH around 8.0, but I'm not sure if that's the sweet spot. What's the ideal range for most corals? My tank's a 50-gallon with T5 lighting, running a protein skimmer, and I do weekly 10% water changes with Red Sea salt.
reef9
Posts: 7
Joined: Tue May 14, 2024 5:28 am

Re: Ideal pH for coral growth

Post by reef9 »

8.0 is decent, but most corals thrive at 8.1 to 8.4. Stability matters more than hitting a perfect number though. What's your alkalinity at? If it's swinging, that could be the real issue. I keep mine at 8.3 with a dosing pump and my Acros love it.
Lardy
Posts: 10
Joined: Fri Jul 19, 2024 7:33 am

Re: Ideal pH for coral growth

Post by Lardy »

Yep, reef9's spot on. Gotta keep that alk steady too. My tank's at 8.2, and the Zoas are popping. You using a controller? Makes life easier if you're messing with pH. I've got a Neptune Apex keeping things chill.
plocka
Posts: 7
Joined: Thu Oct 10, 2024 10:10 pm

Re: Ideal pH for coral growth

Post by plocka »

reef9 wrote: Thu Aug 28, 2025 3:02 am 8.0 is decent, but most corals thrive at 8.1 to 8.4. Stability matters more than hitting a perfect number though. What's your alkalinity at? If it's swinging, that could be the real issue. I keep mine at 8.3 with a dosing pump and my Acros love it.
Exactly this. pH is part of the puzzle, but alk and calcium are just as key. My SPS tank runs at 8.3, alk at 8.5 dKH, and I dose daily. How often are you testing?
User avatar
graye
Posts: 402
Joined: Sat Jan 08, 2022 9:05 pm

Re: Ideal pH for coral growth

Post by graye »

Honestly, if your pH is stable at 8.0 and everything else is in line, I wouldn't stress. My softies do fine at 8.0, but my LPS prefers 8.2. What corals are you keeping? That'll change the game. Also, what's your tank's CO2 like? High indoor CO2 can drag pH down.
stevana
Posts: 8
Joined: Thu Oct 10, 2024 5:34 pm

Re: Ideal pH for coral growth

Post by stevana »

Thanks for the input, everyone. I'll test alk and calcium more often. Mostly keeping LPS and softies right now, with a couple of Montiporas. Tank's near a window, so CO2 might be a factor.
koralux
Posts: 10
Joined: Mon May 09, 2022 1:35 am

Re: Ideal pH for coral growth

Post by koralux »

Window could be sketchy for temp swings too. My pH dips at night, but it's normal. You got a refugium? Macroalgae can help stabilize things. I run chaeto on a reverse light cycle, keeps my pH from crashing.
buddy1
Posts: 4
Joined: Wed Jul 13, 2022 4:22 pm

Re: Ideal pH for coral growth

Post by buddy1 »

I've had luck at 8.1 with my mixed reef. Nothing fancy, just a HOB filter and weekly water changes. My Duncan's been growing like crazy. Maybe try bumping it up slowly? Sudden changes freak corals out.
sandcat
Posts: 6
Joined: Thu Oct 10, 2024 5:09 pm

Re: Ideal pH for coral growth

Post by sandcat »

My two cents: if your corals look happy, don't fix what ain't broke. My pH sits at 8.0, and everything's thriving. But I'm lazy with testing, so take that with a grain of salt. Literally.
User avatar
Riken
Posts: 2
Joined: Thu Oct 10, 2024 4:07 am

Re: Ideal pH for coral growth

Post by Riken »

graye wrote: Thu Aug 28, 2025 6:52 am Honestly, if your pH is stable at 8.0 and everything else is in line, I wouldn't stress. My softies do fine at 8.0, but my LPS prefers 8.2. What corals are you keeping? That'll change the game. Also, what's your tank's CO2 like? High indoor CO2 can drag pH down.
Yeah, CO2's a sneaky one. I cracked a window near my tank, and pH went up 0.2. Cheap fix if that's your issue.
Post Reply