New to Salt, Test strip shows Chlorine, digital shows low ORP?

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pir8radio

pir8radio

0
Jun 13, 2015
14
Chicago, Ill
New to salt water pool, just converted.. Not new to water chemistry, previous experience in cooling tower and saltwater aquariums.

So converted my pool to salt, its a 20k pool with a 60k generator. opened pool just off of generator, water is clearing up each day, just needs a vacuum now. PH 7.4 TDS a little high 6k salt a little high per manufactures suggestion 4100. My fancy brand new SAFE-DIP 6-in-1 Electronic tester says ORP LOW (was showing orp like 137 yesterday, seems to be dropping) however test strips show free chlorine right in the sweet spot... Can't be correct right? I know the generator is working i can see the fine white bubbles in the return line, and the generator is drawing about 197 watts. I know my fancy tester is working, if i mix up some chlorine water it reads... what gives?
 
Welcome! We don’t put much stock in test strip tests. They’re pretty notoriously inaccurate. We recommend a FAS-DPD dropper kit. A more accurate test might give you more help and enlightenment. :)
 
IceShadow said:
Welcome! We don’t put much stock in test strip tests. They’re pretty notoriously inaccurate. We recommend a FAS-DPD dropper kit. A more accurate test might give you more help and enlightenment. :)
Click to expand...

well yea, i have the drop kit too, but the fact that can even get anywhere near "good" on a strip and still show below 130 on the ORP is weird right? I mean I would question the accuracy if i was showing like 400 ish on the orp reading and good on the strip... but the fact that I show any hint of chlorine on the strip, yet no orp is a little weird to me.. was just wondering if someone had an explanation i wasnt thinking of...
 
water is crystal clear, no visible algae, no haze of any type, its really weird, I re-calibrated my ORP meter using a test solution, my well water reads the same as before the re-calibration, and the pool reads low ORP still (low is 100 or below). It's really weird because the chlorine in the drop test and test strips continue to rise. so I shut off the chlorine generator for now.

IMG_1287.jpgIMG_1288.jpg

More info if helpful, I opened my pool, converted to salt, no chlorine or shock used, filtered with an oversize sand filter 24-7 for about 6 days, got to the point where water was foggy but can see the bottom fine. Vacuumed, got the rest of the leaves out, ran sand filter for another day or two. Switched to my DE filter, got the water looking like glass. ORP was at 300 something at one point, chlorine slowly rose to this point AFTER it ate the contaminates in the water, orp dropped over the same time.

This is my same Opening routine minus the shock.
 
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I'm going to be up front: we're sorry, but if you are only going to offer up test strip or OTO test results, then we can't help you.

OTO is extremely imprecise and not accurate for anything other than confirmation that some chlorine is in the water. Not to mention it only shows Total Chlorine, so you don't have any idea if you are looking at FC, CC, or a combination of both. ORP is not especially reliable on a good day, doubly so in a pool with CYA. Which an SWG pool needs to have enough CYA in it as to completely invalidate any ORP readings. Test strips are not reliable. No qualifier, they are worthless through and through. Just throw those stupid things out.

An FAS-DPD test would clear up this confusion immediately. That's why we require it to get chemistry assistance. We don't fly blind here: accurate reliable numbers or bust.
 
??‍♂️ I’m just looking for opinions on the results I have shown above. If I had the answer I wouldn’t be posting here. Who would. Given what you see in this thread and your past pool experience your best guess would be?....... that’s all I’m looking for. I’m not looking fora .5 ppm accurate response. Just a “have you seen this” opinion. I understand the ideal test method you pointed out and thank you, but I’m not really looking for full on chemistry advise.
 
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The problem is we can guess but we can’t even say if the guess is right without knowing the chemistry of the pool. As stated before the OTO test reports total Cl. The test you have goes to 3ppm. If you have that number and do a fas-dpd test it would give free Cl and combined Cl separately. If that test showed for 3ppm a FC of 1ppm and a CC of 2ppm then you might know the problem. You have used the Cl and hence ORP is low. Your 6 way meter shows Cl low is that automatic because of low ORP or does it measure Cl and what is low Cl to the meter does it measure total or free Cl. Most people run 70ppm of CYA in their salt pool and f you have that level of stabilizer and only 3ppm of Cl then it is all tied up by the stabilizer hence low ORP. So without accurate chemistry numbers we could guess all day and that is all we would have is guesses and no real idea of what is going on in the pool.
 
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