FAS-DPD test help

poolnovice1

Bronze Supporter
May 11, 2018
63
Houston
I have a TFT-100 kit. When I add the 5 drops of DPD #3, I get a very, very slight change in color. If I glanced away and looked back, I would say it's clear. But I can definitely see that it's 'less clear' as I'm adding the drops.

So question is, can I interpret this result as between 0 - 0.5 CC? If the CC is 0.5, is there an obvious change to pink/red?

I'm asking because I always considered this as 0-0.5. But I took a water sample to Leslie's just to see and they say I have a CC of 0.95.
 

Texas Splash

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Jun 22, 2014
31,460
Texas, San Antonio/Marion, South-Central Area
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Novice1, I wouldn't try to struggle with analyzing the shades of yellow or orange on that OTO viewer for FC just yet. With the TF-100 you have the FAS-DPD which is the gold standard. Use that for a while first to get confident of your FC and CC readings. Once you do that, then you can bounce back and try the OTO viewer to compare what the color shade should look like.

For the FC test, fill the chlorine tube with use one generous scoop of powder, mix and count drops until it goes from Barbie pink to clear and divide that answer in half. Example - 12 drops equals an FC of 6.
 

Kevinr14

Silver Supporter
Mar 8, 2021
237
Chandler, AZ
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Don't trust the pool stores.

Novice1, I wouldn't try to struggle with analyzing the shades of yellow or orange on that OTO viewer for FC just yet. With the TF-100 you have the FAS-DPD which is the gold standard. Use that for a while first to get confident of your FC and CC readings. Once you do that, then you can bounce back and try the OTO viewer to compare what the color shade should look like.

For the FC test, fill the chlorine tube with use one generous scoop of powder, mix and count drops until it goes from Barbie pink to clear and divide that answer in half. Example - 12 drops equals an FC of 6.

I believe the OP is referring to the CC test in which it is supposed to turn back to pink if CC is present.

Mine also always turns a very, very slight pink color which leads me to believe it's less than .5. you could always use a 25 ml sample and count the drops as .2. I have yet to do this because it honestly hasn't been a concern.
 

poolnovice1

Bronze Supporter
May 11, 2018
63
Houston
Don't trust the pool stores.

I believe the OP is referring to the CC test in which it is supposed to turn back to red if CC is present.

Mine also always turns a very slight pink color which leads me to believe it's less than .5. you could always use a 25 ml sample and count the drops as .2. I have yet to do this because it honestly hasn't been a concern.
Yes, that's right. I don't even know what an OTO viewer is. So sounds like if it's .5 or more, it'll be a noticeable red.
 

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Jun 22, 2014
31,460
Texas, San Antonio/Marion, South-Central Area
Pool Size
17888
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
CircuPool RJ-45 Plus
I believe the OP is referring to the CC test in which it is supposed to turn back to pink if CC is present.
I see. Thx. I would probably still use th1 FAS-DOD though if someone is new for better reliability.

I don't even know what an OTO viewer i
Your TF-100 came with the FAS-DPD (powder & drops) and a basic OTO plastic viewer and chlorine drop bottles (yellow caps). That OTO viewer has the pH column on the rights and CL on the left. That CL is a very basic (cumulative) total of FC and CC to equal Total Chlorine. It's used by folks who have fine-tuned their chlorine color viewing skills or only want to know a general presence level of chlorine. The FAS-DPD is always more accurate, but you can practice with both.
 
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