Why is my PH rising?

[Bblinks]

"The pH of marine aquarium water is intimately tied to the amount of carbon dioxide dissolved in the water. It is also tied to the alkalinity. In fact, if water is fully aerated (that is, it is in full equilibrium with normal air) then the pH is exactly determined by the carbonate alkalinity The higher the alkalinity, the higher the pH, and equilibrated with air having extra carbon dioxide as might be present in a home (1000 ppm). Clearly, the pH is lower at any given alkalinity when the carbon dioxide is raised. It is this excess carbon dioxide that leads to most low pH problems for reef aquarists"
That was a quote from one of Randy Holmes articles. With fresh o2 in the house it could affect the ph in our aquarium , also if your refugium has seen good growth over the last bit, it could also take up amount of co2 in the tank and by reducing co2 level we know it will also raise ph. Just food for thought.

[The Grizz]

According to my Ph probe my tank is sitting @ 9.09.

[Lampshade]

When my Halides turned on my PH would always go up .2 or more after i moved my controller to the new location. Moved some cords around, and made it spike up .5 when the halides where on.

Make sure you're not running the wire near ANYTHING electrical. They gain 0.41mV per PH, so having electrical wires around them can easily change that. Just mentioning in case you've moved some wires around recently that could be causing it. It's most likely the increased O2, lots of people have summer/winter PH levels because of more windows being open.

[Gripenfelter]

Probe needed re-calibrating. Thanks everyone.

[Gripenfelter]

Still goes up. Not as much but still going up.

When I re-calibrated the probe it went to 8.13. Down from 8.37. All yesterday it was at 8.19. This morning when the lights came on it was 8.22.

I have my RO/DI unit set to run for 30 mins per day to top off the water.

Nitrates and Ammonia are 0.

PH test verified probe reading.

Sump gets lots of bubbles from overflow.

[Myka]

How old is the probe and what brand? Often times when probes start dying they start losing their calibration.

Fwiw, CO2 isn't the only cause on low pH. Decaying organic matter will lower the pH as well which is why many tanks that have high nitrate also have low pH.

Originally Posted by The Grizz

According to my Ph probe my tank is sitting @ 9.09.

I doubt that is accurate. Have you calibrated lately?

[Gripenfelter]

I verified the probe reading with an actual PH test and it's accurate. Seems to be stable though. Still sitting at 8.19 over night and 8.22 during the day so not bad.