OTO or DPD?

jeffcessna

Well-known member
May 14, 2009
60
Tennessee
I cant seem to find a definite answer and was wondering if you only have either an OTO or DPD test kit (like I do) which one would be better to use? :?
 

duraleigh

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In The Industry
Apr 1, 2007
31,675
Sebring, Florida
For the kind of testing needed to manage your pool really well, I would say neither. Most people find the FAS/DPD chlorine test an invaluable part of their testing and wouldn't use anything else.

OTO tests for the presence of chlorine but it's accuracy is good for little else. I have never used DPD.
 

JasonLion

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May 7, 2007
37,880
Silver Spring, MD
It depends on what you are doing. They both have advantages and disadvantages, just in different places. DPD can distinguish between FC and CC, which OTO can't. On the other hand DPD will show zero chlorine when the FC level is actually very high. DPD is noticeably better at distinguishing between FC levels around 3 to 5.

The FAS-DPD test is much better than either of those in nearly every way.
 

Isaac-1

TFP Expert
LifeTime Supporter
May 10, 2010
6,711
SW Louisiana
I find the OTO test kit included in the TF100 kit to be handy for quick ball park chlorine level checks, but it is a BIG ballpark and it is also handy as a double check against the FAS-DPD, I have used tests that were DPD in the past, they are somewhere in the middle, a little easier than doing the FAS-DPD, but have the color matching problems of OTO.

So

OTO - quick easy 1 step ballpark total chlorine number

DPD - mid level test but tells you both FC and CC (at least in a ballpark)

FAS-DPD little more work than DPD, but tells you to the .5 PPM level for both FC and CC and best of all NO COLOR MATCHING just pink or clear
 

poolgirl22

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LifeTime Supporter
Apr 14, 2010
595
Stephens City, VA
ditto what isaac said.

since my target on the high end is 9 and my minimum is 4 or 5, there's a biiiiigggg range there on the OTO.

I use FAS DPD every day. Sometimes twice.
 

jeffcessna

Well-known member
May 14, 2009
60
Tennessee
I went to my local pool store (Pool and Spa Depot) and asked to see if they maybe carried the FAS-DPD test and they didn't have any idea what I was talking about. I tried to explain to them what it was and the man behind the counter told me, "We don't get that technical." I was taken aback and decided that there was no way I was going back in that store again....ugh. I am going to have to eventually just get the FAS-DPD test kit so I can test accordingly. For the time being I will continue to use the OTO for daily tests and the DPD maybe every other day to TRY to verify.
 

jeffcessna

Well-known member
May 14, 2009
60
Tennessee
I was just looking at the Taylor website and I can just order the R-0870 powder and the R-0871 drops for the FAS-DPD test kit instead of ordering the entire kit.
 

Isaac-1

TFP Expert
LifeTime Supporter
May 10, 2010
6,711
SW Louisiana
You would also need R-003 for the combined chlorine part of the test, a graduated cylinder to get the correct amount of water and the little scoop for the powder. To me is seems easier to order the K-1515 kit as you get a box to keep it in, etc. Note if you use non-chlorine shock like HTH Shock n Swim you want to get K-1518
 

chem geek

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Mar 28, 2007
12,082
San Rafael, CA USA
You can either get the Taylor K-1515 FAS-DPD chlorine test kit here or you can get the FAS-DPD chlorine test kit from TFTestkits here with the latter kit having 2.67 times the volume of reagents so is less expensive per test.
 

jeffcessna

Well-known member
May 14, 2009
60
Tennessee
I don't use shock at all. Just the BBB method :goodjob: Is there any preference as to which test kit to get for just the FAS-DPD test??
 
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