Settle a bet about testing?

Hello all,
My friend at work believes that all he needs is an OTO tester to check his chlorine. He says that when he puts the five drops in the yellow side, the color you first get is his Free chlorine, and after a few minutes, the color you get is your total chlorine. If there is a big difference, you have combined chlorine, and should shock.

I told him that I did not think that was correct, and that you need a DPD testkit to accurately test FC, CC and TC. Even if he was correct, if your CC is more then .5ppm, it should be addressed, and a person could not even tell a .5ppm color change.

Am I right? I don't understand how someone could spend over $20,000 on an inground pool, $700 on a pool light, but not spend more then $4.00 on a testkit.
I love both my "old" PS232 and now my new PS234 testkit. Thanks Ben!

Frank D.

He's wrong, but why would he believe us?

Perhaps Waterbear can explain the underlying chemistry of OTO testing to show that only TC is revealed.

I don't understand either why people won't spend less that $100 on a good test kit after having spent $20,000, $50,000, or $150,000 on their pool and landscaping.

Maybe Ben and I can debate THAT in the China Shop!:D

Carl, $100 :eek: - I just bought my ps234 and it cost me <$75 with shipping! And I got it in 10 days!! (BTW, I'm loving the kit, no learning curve [vs Taylor 2005] and it's quicker - all I have to do is figure out the 'wrist shakes' to get the water to the proper level for the tests, I've had to refill the test chambers more times this week than I've had to in the last 5 years ;) )

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Originally Posted by faithfulfrank

Hello all,
My friend at work believes that all he needs is an OTO tester to check his chlorine. He says that when he puts the five drops in the yellow side, the color you first get is his Free chlorine, and after a few minutes, the color you get is your total chlorine. If there is a big difference, you have combined chlorine, and should shock.

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While in Home Depot a couple of weeks ago, I saw that the test kit they were selling said exactly that. Is it accurate, I doubt it. Is it accurate over 5 ppm? No Way. I would even go further to say that if you compared his test to yours (assuming your testing with FAS-DPD) yours would be more accurate every time. As Carl said, he probably won't believe you any way. His loss.

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Originally Posted by Carl D

I don't understand either why people won't spend less that $100 on a good test kit after having spent $20,000, $50,000, or $150,000 on their pool and landscaping.

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Excellent point! You'd think a $100 investment to protect this HUGE investment they made is going to break the bank. I guess it can be attributed to the fact that most people want something for nothing...

Dave

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Originally Posted by waste

all I have to do is figure out the 'wrist shakes' to get the water to the proper level for the tests, I've had to refill the test chambers more times this week than I've had to in the last 5 years ;) )

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I know exactly what you mean. Duraleigh (Dave S.) mentioned once that his wife was using a syringe or baster or something like that. I went to Walgreen's last night and bought a medicine dropper for babies. It is a little small but should probably work great for OTO, PH and FAS-DPD. Plan on trying it out tonight.

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Originally Posted by waste

Carl, $100 :eek: - I just bought my ps234 and it cost me <$75 with shipping! .............

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Waste,
I think CarlD was saying Ben's kit costs less than $100, and why would people not invest in a good kit that costs so little compared to the thousands of $$$ they spent on the pool??

could be wrong, though!! :)

No, Grace, that's exactly what I was saying.

At one time I used an OTO on my stand alone spa and I can tell you from experience that although not very accurate, you can tell if you have high CC by the color change over time. The initial color would tell you might have say 1 ppm of chlorine but have 3-5 minutes, the color would significantly darken indicating 5 ppm or more. This is not a good way to tell how much CC you have only that you have too much.

To all, I agree! Mas, the little kits, and even test strips (if they're good) can tell you if you're within the 'proper' range, but you need a 'real' kit to dose the pool -I think that's what you were getting at. Grace, do you think I'm crazy enough to take on a moderator?, I simply misread his post (happens all the time here, sorry to be part of the 'misunderstanding what someone posted' group :) , but thanks for the clarification :cool: David, the kit came with a bottle that holds enough to do all the tests, my problem is that, since it won't fit in the kit, I can't carry it with me at work (convieniently) - Looks like I'll be 'shaking out the extra water', but I love the kit :) . Sorry if anyone misunderstood what I tried to say ;) - Waste

OTO will accuately tell TC. The problem with testing FC is that the color keeps darkening for about 2-3 minutes and when are you supposed to read the FC? I have seen kits that say read it in the first 3-5 seconds (a no name cheapie comparator I picked up about 8 years ago at my spa dealer), ones that say read it at 15 seconds (Walmart Aquachem), and ones that say read it within 30 seconds (a 4 way kit that I saw in a pool store, private label)...which one is right? They are all using the same chemcial for testing! I believe you can get an idea if you have CC with OTO IF the level of combined chlorine is high, but then again, I can smell that with my nose! If you want it to about 1 ppm then you need a DPD test, if you want it more accurate you need either a DPD test with a colorimeter or an FAS-DPD test. I do know that most states do NOT allow OTO testing for commercial pools and require either DPD or FAS-DPD for precisely this reason....you cannot accurately test for FC with OTO! The other problem with OTO testing is the differenced in the darkness of the yellow color are very small and hard to distinguish when they are less than 1 ppm apart! You can see this by looking at OTO comparators. The shades of yellow are very close. Even with TC I feel it is an approximation at best. (But OTO is best for a 'quick and dirty' check on your chlorine levels.