How important is pH to you?

Biff0rz · May 5, 2026

So, some context -

I’m currently running kalk, sda (recently removed), and a CaRx, along with a CO2 scrubber on the skimmer. With all of these combined, my pH was typically 8.25–8.5, occasionally it'd hit 8.6 with fresh media and lower house co2. When it was high I noticed good PE and growth... but it’s difficult to concretely attribute the two to the high pH. Recently, I started noticing signs of precipitation (clumping sand, deposits), and at the same time my alkalinity dropped to 7.2–7.4 (normally 8.3-8.6). But a couple a weeks ago when it dropped I was unable to bring alk back up even when increasing kalk, sda, and the CaRx. I did some research and asked some locals their advice.

I believe I was driving pH high enough to induce abiotic precipitation, which was effectively consuming the additional alkalinity I was adding. To validate this, I removed sda and switched to NaHCO3. Since doing that, my pH has dropped to 8.0–8.3 (expected), precip appears to have stopped, and alk is slowly starting to rise again.

At this point I’m debating what to do next. I don't really want to let pH fall much below 8.0, but I may be overvaluing higher pH.

For those running systems long-term -

Do you actively manage pH, or let it settle where it lands?
For those consistently running 8.5+, how are you avoiding precipitation issues?

Note: when I was having precip, Ca and Mg were managed, they ranged from:

Ca: 420–460
Mg: 1320–1360

Thanks!

exnisstech · May 5, 2026

I'm only 3 years onto my SPS tank. I ran the first 2+ years with pH running 7.6 -7.9 daily swing and and I think the tank did fine. I installed a skimmer for aeration and ran an outside airline last October and now I'm getting pH of 8.0 - 8.3 daily swing. Coral growth did increase as my alk consumption went went from using 35ml AFR daily to 60ml in less than 2 months.
I'm not willing to chase pH any further than adding the skimmer because accelerated growth isn't that important to me and it is the only noticed improvement I've seen from higher pH. If I was fragging and selling I might but I'm already breaking pieces when I work in the tank and have to pitch them.

Mr. Mojo Rising · May 5, 2026

I haven't measured ph in years, I don't feel like I'm missing out on anything, my corals grow thats all that matters to me

BryanM · May 5, 2026

Biff0rz said:
So, some context -

I’m currently running kalk, sda (recently removed), and a CaRx, along with a CO2 scrubber on the skimmer. With all of these combined, my pH was typically 8.25–8.5, occasionally it'd hit 8.6 with fresh media and lower house co2. When it was high I noticed good PE and growth... but it’s difficult to concretely attribute the two to the high pH. Recently, I started noticing signs of precipitation (clumping sand, deposits), and at the same time my alkalinity dropped to 7.2–7.4 (normally 8.3-8.6). But a couple a weeks ago when it dropped I was unable to bring alk back up even when increasing kalk, sda, and the CaRx. I did some research and asked some locals their advice.

I believe I was driving pH high enough to induce abiotic precipitation, which was effectively consuming the additional alkalinity I was adding. To validate this, I removed sda and switched to NaHCO3. Since doing that, my pH has dropped to 8.0–8.3 (expected), precip appears to have stopped, and alk is slowly starting to rise again.

At this point I’m debating what to do next. I don't really want to let pH fall much below 8.0, but I may be overvaluing higher pH.

For those running systems long-term -

Do you actively manage pH, or let it settle where it lands?

For those consistently running 8.5+, how are you avoiding precipitation issues?

Note: when I was having precip, Ca and Mg were managed, they ranged from:

Ca: 420–460

Mg: 1320–1360

Thanks!

my tank runs 7.8 to 8.2. I do not try to raise it.

X-37B · May 5, 2026

I run kalk 24/7 and a carx.
Kalk keeps my nighttime ph 7.9-8 with day time 8.3. I run my alk at 7.5. No problem with growth. I run 2 oversized skimmers, one with ozone and no scrubber.