[lgerold]

Hi!

Unfortunately, I do think that the reading is accurate. I took a sample in to a water testing lab (they contract to do well testing, city water testing, etc) and their test showed the PH at 7.85 (dark photoperiod.) They guarantee accuracy to plus or minus 0.01. I figured, since the water was taken at 7 am, after lights out (except on refugium) for 9 hours, that the PH would be at it's lowest, and that when the lights were on (as they were yesterday) for several hours, that the PH would raise to 8 or above. Didn't happen.

I calibrated the new meter using PH 7.01, 4.01, and 10.01. I first used the 7.01 and 4.01 that came with the meter, and figured since the PH is supposed to be to the right of 7, I should probably calibrate using 10.01. Went to do that and it was already calibrated perfectly.

The Pinpoint PH Meter is running on a brand new 9 volt battery. The reading is steady, after a few seconds of jumping around when first put into a solution. The meter is running constantly now on the tank.

My alk has been dropping all summer since last spring when I first set up the tank (after erroneously adding buffer in an ignorant attempt to raise my low ph). Last spring, my alk was up to 5.71.

So, last week, when the alk fell to 2.74, I used one dose of Super Buffer to raise the alk, which went up first to 4.5, and a bit more within a week to the current level of 4.85. I expected much less of an alk boost. I know (I think?) that at a lower PH, higher alk and calcium levels are needed to make the calcium available to the corals.

I'll check the meter on the mixture you suggested.

Thanks!

Lucy