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HM Digital PH & TDS meters

3295 Views 4 Replies 3 Participants Last post by  ebross67
Has anybody had experience with this brand of (HM) PH meter and TDS meter? I bought both and I'm having issues with them. The PH meter will not stay calibrated any longer than 24hrs. Is this typical for a PH meter. My other question - both meters temp gauge is off by 3-5 degrees. I have a couple saltwater temp probes and a couple kitchen temp probes that read correctly. Is it typical for the temp gauge on PH and TDS meters to be off? Thanks.
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Never herd of them.My Pinpoint ph stays accurate all the time.
Thanks for the input Loverotties, anybody else have info on HM, thanks.
I have use the HM Digital TDS-3 and COM-100 for years with zero issues. The COM-100 is the best hobbyist grade meter on the market.
What makes you think the temp is off on both? Are you sure what you are comparing them against is accurate?
Thanks AZDesertRat, I know they are off because I have 3 coralife digital thermometers, and two kitchen liquid thermometers. The five all show the same reading within .2 degrees and the two HM meters show 3 degree difference (it's weird).

If the calibration of the HM PH Meter is off will it effect its thermometer calibration?

I bought these meters to make life a little simpler, but it's becoming more of a headache.

I bought a refractometer from Dr. Foster Smith (the blue model), and some calibration fluid. I calibrated the refractometer and thought it was good to go. A couple days later I tested it with the calibration fluid again and it was off. I screwed the screw all the way in, and it can't go any further, but it says it's still off by 1PPT (in the direction it needs to go).

The one meter I did buy and works great is the low range phosphate digital meter by Hanna. I have .02ppm of phosphate, yeah I think.
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