FernBluffReef
Active Member
I have a question about PH testing that I'm hoping someone can shed some light on.
RedSea 112 Gallon display / 31 Gallon sump. 14 months new, started with macro rock. Well stocked with fish. Couple clams, moderate coral mostly LPS and a large nem.
PH was historically averaging ~7.7-7.9 in the AM using a Hanna colorimeter. As a result, I constructed myself a DYI Recirculating scrubber to raise the PH which is now working great
Weekly tank testing results from this morning
- According to Hanna colorimeter HI790 reads 8.5 which I believe to be high as the Hanna colorimeter has always been around .2 higher than any of my other testing methods. The colorimeter never reads less then 8.3 since installing the CO2 scrubber.
- PH controller in-tank - Milwaukee MC122 PH controller - says 7.9
- Hanna PH checker (HI98103) - hand held probe reads 8.3
- So basically, all over the Map. All of the above are rated +/- .2 accuracy hence 7.9 to 8.5 seems like a wide range
I just got the PH checker above from another reefer last weekend for a deal, so I can quickly test all my tanks. I calibrated it last weekend and checked the calibration of the Milwaukee at the same time - both with the same calibration fluids pre-warmed in the tank. This was during the day and both the newly calibrated Hanna PH checker, and the Milwaukee read the exactly same at that time.
The CO2 scrubber is set to turn on right at the threshold of 7.9-8.0 and shutoff right at the threshold of 8.2-8.3. It's on this morning as to be expected, and I tend to believe the in tank reading from the Milwaukee vs. the others.
Question, is there really expected to be that much difference between a stable probe in-sump vs. a real-time reading with a colorimeter or handheld probe? The in-tank slowly goes up during the day as expected and slowly down once the lights go off as expected. The other testing methods seem to read about the same day or night save if tested first in the morning and peak of the afternoon when you expect to see a greater difference.
I know I should not worry too much about PH but given I went thru all the effort to build and install the recirculating CO2 scrubber at least want to know its working - it is:) . I also know, one should generally pick one test method and stick to, my only real reason for continuing to test PH as part of my weekly testing is to help identify when the in-tank probe maybe starting to drift and either needs recalibration or replacement. As of right now it's only ~30 days new probe and again when I calibrated the Hanna checker handheld probe, I also double-checked the Milwaukee with the same fluids, and it did not require any adjustments. Using two point calibration 7.01 and 10.01 calibration fluids
Thanks for the insight
P.S. ~ 2 weeks ago, I tested with a RedSea PH test I have around in the morning. It read about the mid-point between the Milwaukee probe and the Hanna Colorimeter at that time.
P.P.S. I tested my other tank this morning with the Hanna PH checker and it read 8.1, so .2 lower than the main display which is largely consistent with what I'd expect - that the other tanks PH would be quite a bit lower as it does not have a scrubber.
Full test results from this morning if adds any value
- Salinity 35.1
- Temp 76.50
- Nitrate 9.6
- KH 7.7 (a bit low usually I shoot for Low 8s and understand helps with PH stability)
- Phosphate .09
- Calcium 441
- Mag 1,445
RedSea 112 Gallon display / 31 Gallon sump. 14 months new, started with macro rock. Well stocked with fish. Couple clams, moderate coral mostly LPS and a large nem.
PH was historically averaging ~7.7-7.9 in the AM using a Hanna colorimeter. As a result, I constructed myself a DYI Recirculating scrubber to raise the PH which is now working great
Weekly tank testing results from this morning
- According to Hanna colorimeter HI790 reads 8.5 which I believe to be high as the Hanna colorimeter has always been around .2 higher than any of my other testing methods. The colorimeter never reads less then 8.3 since installing the CO2 scrubber.
- PH controller in-tank - Milwaukee MC122 PH controller - says 7.9
- Hanna PH checker (HI98103) - hand held probe reads 8.3
- So basically, all over the Map. All of the above are rated +/- .2 accuracy hence 7.9 to 8.5 seems like a wide range
I just got the PH checker above from another reefer last weekend for a deal, so I can quickly test all my tanks. I calibrated it last weekend and checked the calibration of the Milwaukee at the same time - both with the same calibration fluids pre-warmed in the tank. This was during the day and both the newly calibrated Hanna PH checker, and the Milwaukee read the exactly same at that time.
The CO2 scrubber is set to turn on right at the threshold of 7.9-8.0 and shutoff right at the threshold of 8.2-8.3. It's on this morning as to be expected, and I tend to believe the in tank reading from the Milwaukee vs. the others.
Question, is there really expected to be that much difference between a stable probe in-sump vs. a real-time reading with a colorimeter or handheld probe? The in-tank slowly goes up during the day as expected and slowly down once the lights go off as expected. The other testing methods seem to read about the same day or night save if tested first in the morning and peak of the afternoon when you expect to see a greater difference.
I know I should not worry too much about PH but given I went thru all the effort to build and install the recirculating CO2 scrubber at least want to know its working - it is:) . I also know, one should generally pick one test method and stick to, my only real reason for continuing to test PH as part of my weekly testing is to help identify when the in-tank probe maybe starting to drift and either needs recalibration or replacement. As of right now it's only ~30 days new probe and again when I calibrated the Hanna checker handheld probe, I also double-checked the Milwaukee with the same fluids, and it did not require any adjustments. Using two point calibration 7.01 and 10.01 calibration fluids
Thanks for the insight
P.S. ~ 2 weeks ago, I tested with a RedSea PH test I have around in the morning. It read about the mid-point between the Milwaukee probe and the Hanna Colorimeter at that time.
P.P.S. I tested my other tank this morning with the Hanna PH checker and it read 8.1, so .2 lower than the main display which is largely consistent with what I'd expect - that the other tanks PH would be quite a bit lower as it does not have a scrubber.
Full test results from this morning if adds any value
- Salinity 35.1
- Temp 76.50
- Nitrate 9.6
- KH 7.7 (a bit low usually I shoot for Low 8s and understand helps with PH stability)
- Phosphate .09
- Calcium 441
- Mag 1,445
