accute pH spike

[jd474]

hi all, so when i came home from work tonight around 10 pm, i immediately noticed my orange capricornis beaming hot neon/slightly-bleached pink coloration and wondered what was going on. i have approx. 80 sps corals in the tank, and almost all the montiporas were looking the same, along with 2 or 3 acropora colonies. everything else looked normal, and all had (usual) excellent polyp extension. when i checked my controller, the pH probe read 8.6 (and was confirmed with pH calibration solution +/- .02, anyway). my usual swing is 8.1 - 8.3 over the course of the day, but i've never seen it this high. i quickly dosed ~500 ml soda water, and it has since come down but i still don't know why it was so high. any ideas? nothing was changed recently, and the system has been stable and running for 3 years. i don't dose any hydroxides or limewater, and i do run a Ca Rx which makes me surprised it was at 8.6. all other params. are normal. i am pretty experienced, but again, i haven't seen this before. any help would be appreciated.

 

[bertoni]

That's fairly strange. Most pH spikes are due to supplements or limewater. Usually, 8.6 is not high enough to cause any problems. I'd watch the tank, and make sure all the pumps and skimmers were operating properly. Poor aeration combined with a lot of photosynthesis can drive pH up.

 

[jd474]

i don't think aeration is an issue, the D.O. runs about 6.8 meq/l and 105% saturation, tank turnover is 20+/hour, with a large recircuating euro-reef skimmer that are both working. again, it really only bothered the montipora spp., all of the other SPS/LPS look perfectly normal.

 

[bertoni]

That's very odd, then. Maybe something got into the system, or there was some issue with the pH probe.