rising pH making me concerned

[wbradenpt]

with my old setup i was never able to get pH above 8.0.
recently put everything from old 140g tank into new 180g tank, and added calcium and kalk reactors. when first set up, the pH ranged from 7.8 overnight to 8.0 near end of lighting cycle, this was with only calcium reactor running.
once kalk reactor was going, it slowly crept up and went from 8.2 to high of 8.4. then i turned off kalk reactor.
after a few days it was going between 8.1 and 8.3, so i started kalk at a much slower rate, and it went back to 8.2 to 8.4.
then yesterday i noticed it was at 8.5 near end of lighting cycle. stopped kalk entirely.
the lowest it went overnight was 8.4. i assume it is going to go up again when the lights go on.
is this too high?
should i be concerned?
any advice?

[kenargo]

8.2-8.4 is quite acceptable; I wouldn't suggest going any higher than 8.4 (though I have heard some people running tanks at 8.5).

I also run CO2 and Kalk reactors. What I do is to have a valve that switches from RI/DI (straight) or RO/DI (through the Kalk reactor) depending on PH (< 8.4 gets Kalk, higher gets plain RO/DI) and this have worked very well for me. The valves where very inexpensive and I can send you a link if that interest you.

[MCsaxmaster]

That's pretty close do ideal actually. Mean pH for the surface ocean nowadays is down to 8.20 due to elevated atmospheric CO2. Before about 1750 (industrial revolution) the pH averaged 8.31 and was 8.45 during the last glacial maxium. I'd say a max of 8.5 - 8.6 at the end of the light cycle is nothing to be overly concerned about. In highly enclosed areas on reefs in nature the pH has been measured as high as 8.9 during the day (that's pretty uncommon though). I think that 8.2 - 8.4 is a very nice target for pH.

cj

[wbradenpt]

thanks for the input. feel better already. what i do now is use a dosing pump when i run the kalkwasser reactor. but i have a level controller that automatically tops off tank with ro water. got home today and pH was still only 8.4. will sleep just fine tonight.

[MCsaxmaster]

Also, I'd recalibrate the pH meter. They drift over time. Besides, I'm not that trustful of pH probes in sea water being accurate to more than +/- about 0.05 (precise yes, accurate no) and that includes very good quality ones. Actually, I don't trust commercial buffers (at least cheaper ones) to be much more accurate than that either ;)

cj