pH trending up

celebrityovernight · Oct 17, 2018

Hey R2R, I been noticing my pH in my 300 reef started trending up slowly recently. Back in mid September, my pH would bottom out at 8 at night and peak to 8.2 throughout the day. Slowly since, the peak has started to climb, and is now reaching 8.38 and bottoming out at 8.23. The tank is fairly new, and I started adding corals in it since beginning of September. I run a calcium reactor and kalk reactor to replenish alk and calcium. I'm currently not dosing anything else at the moment. I do use a hose that takes fresh air from the outside to inject it into the skimmer. Parameters have remained stable throughout, alk 8.5 calcium 450 mag 1500. I don't see any adverse effects in the corals and they seem to be growing okay. Any ideas to why pH is climbing slowly?

rc1626 · Oct 17, 2018

What are you using to measure ph? If using a probe have you recalibrated it recently. Just recalibrated mine and my ph readings went from 8.2 during the day to about 8 now. Mine was obviously out of calibration.
Just a thought.

celebrityovernight · Oct 17, 2018

rc1626 said:
What are you using to measure ph? If using a probe have you recalibrated it recently. Just recalibrated mine and my ph readings went from 8.2 during the day to about 8 now. Mine was obviously out of calibration.
Just a thought.

It can very well be that that the probe has gone out of calibration. It was brand new however and was just calibrated and installed back in mid september. I might have to recalibrate and see what it does.

rc1626 · Oct 17, 2018

I guess anything is possible. Wouldn't expect a ph probe to lose calibration that fast. In my experience my ph probes tend to drift upward on their readings over time (usually months). Re-calibrate it and see what happens. Calibration fluids and a couple of minutes is all it will take.
BTW to have normal ph readings like that would be great. My high is typically around 8 during the day and at night my low is around 7.8. I'm assuming this is based on my lighting schedule and its relation to gas exchange. That's with my skimmer getting fresh air from outside.

Randy Holmes-Farley · Oct 20, 2018

Accurate or not, those values are fine. pH never gets too high on its own if not adding high pH additives (well, maybe in poorly aerated aquaria it might at the peak of the light cycle).