Re: Oxidation Reduction Potential -- HELP
As Waterbear noted, I don't care for Hanna products. I have a box full of old, useless portable ORP, pH and TDS meters made by Hanna! At the time I bought them, I was still listening to the siren call of "better pool water through high technology". Hanna's products then (15 years ago) worked when new, but were very poorly made, and broke or failed promptly! I don't *know* that they are still making their products the same way . . . but the cases are still the same! (I should note, in all fairness, that I had pretty good success for the price with their electrodes.)Originally Posted by hamop78
The reason to avoid meters in testing your pool is the same reason test strips should usually be avoided: they don't work well for the purpose!
Strips are inherently not very accurate.
Some meters are capable of giving extremely accurate readings, depending on construction and quality . . . but only if calibrated frequently and used properly. That "if" is a very big one.
In addition, only pH meters directly measure something of importance to pool owners. In spite of their complexity, they have a place in pool treatment, simply because thousands of pool owners have impaired color perception, making it difficult to use phenol red color-match tests reliably. One of my projects for this winter is to find a portable pH meter reliable enough to be built up in to a add-on replacement component for the pH test in my kit. However, it will NOT be recommended for everyone with an extra $110 or so to spend!
But, the other meters -- ORP and TDS -- measure something that's essentially useless to pool owners. Both measure something you DON'T need to know (redox potential OR aqueous conductivity) and then use it to guess at (infer) something you do need to know (chlorine level OR overall water condition).
Using a $2,000 Orion mV meter and ORP probe to measure your pool's chlorine is sort of like using a $500,000 X-ray machine to take family photos. It's certainly high tech, but it's still pretty useless for the purpose!
Using a $100 Hanna ORP meter to measure your pool's chlorine is more like using trying to use a TV-advertised "Ronco Miracle Slice & Dice Stamp and Serve Food Chopper" to fix fish for supper -- it not only doesn't work well for YOUR purpose, it doesn't work well for ANY purpose!
High technology doesn't help when it delivers results that aren't what's needed!
But the real secret here is that, apart from the LCD readouts, both ORP and TDS instruments are "old-tech", having been around for more than 50 years! What's more, they usually are often NOT used in water treatment, for the same reasons that they aren't useful in pool treatment: they simply don't measure what water treatment plant operators need to know. And, where they are used, the are monitored and calibrated frequently. The reason they have to be calibrated so often is that there's no consistent relationship between ORP and chlorine levels, or between conductivity and TDS, much less overall water quality.
Calibration just means that the machine's guesstimate is adjusted so that it's right. But, just guess what's used to calibrate the expensive high technology ORP based chlorine meters? Yep, it's the inexpensive DPD-FAS test used here for pool chlorine measurement!
The conclusion is simple: high technology pool measurement equipment is NOT a means to better management.
Rather, the gadgets (with the single exception of pH meters for those with impaired color perception) are the goal themselves. All of us Y-chromosone-types have an inbred, genetically driven, tendency to fixate on electronic gadgets and female chests. Jeri Ryan exploited this perfectly as Star Trek's Seven of Nine. No, I'm not saying that's all bad. I like my Y-chromosone, thank you very much. What's more, both my wife and I both enjoyed Star Trek - Next Generation, though she didn't find Jeri Ryan's character quite as fascinating as I did.But I am saying that gadget-envy does not lead to better pool management, and consequently, doesn't really belong in the general PoolForum areas.
I put it on my winter to-do list, and promise I'll try to add a gadget-lovers section to the forum by next year (2007). But, meanwhile, I'm moving most of this thread to the China Shop!
Best wishes,
Ben
"PoolDoc"
NOTE for MODS: I'm leaving thread unlocked for the moment, but if it veers back into 'gadget-tech', it should be locked. Until I can create a 'Gadget-tech' section, such threads belong in the China Shop.
Reply With Quote
