1. ## My Memorization Technique

First, I want to Thank the TFP community for educating me with Pool School. I learned more reading hours of posts and reading the Pool School articles than I have EVER learned in all my years of pool care put together.

I always thought before coming here: Chlorine should be 3 ppm (ideal). Anything below 2 is not enough and above 3 is too much.

I always figured stabilized is superior to stabilized, though I did not realize that ANY dry chlorine is has an additive such as calcium or CYA. I had no idea what the difference was between Cal-Hypo and Tri-Chlor and that one leaves calcium and the other leaves CYA. I did not realize that Tri-Chlor, the stuff I had been using adds 6ppm of CYA for every 10 ppm of chlorine.

Hence, if my pool consumes 2 ppm per day, in 5 days I would have added 10 ppm FC to maintain levels, but left my CYA 6 ppm higher. Being the ideal numbers are 30 - 50 (except for salt water)... this would only take a few weeks to screw up the CYA level making it too high.

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NOW ON TOPIC:

I read this and love it:

Pool School - Chlorine / CYA Chart

Here is my memorization technique:

Take the first number and add one (1). The first number in 20 is 2... 2 + 1 is 3. You could also look at it as 20/10 + 1, but that starts to look like a formula.

20 CYA is Target 3 ppm (2 + 1 is 3)
30 CYA is Target of 4 ppm (3 + 1 is 4)
40 is 5 ppm
...

Quits working at 100 (tipple digits), but water is usually screwed up to ever get that stabilized.

Anyway, this got me to notice:

Pool stores sell these:

Taylor K-1001 (DPD):
.5 ppm to 5 ppm (Nothing higher than 5. Hollow COW - useless if your CYA is > 40,)

Taylor K-1000 (OTO):
.5 ppm to 5 ppm (again same problem)
Can't be beat for the \$6 the kit costs though.

How can they sell these maxing out at 5 ppm Chlorine in good conscious when 30-50 CYA is Recommended, and above 40 CYA you need MORE than you can measure! (i.e. at 50, you need 6 ppm). It's insanity! No wonder they sell so blasted much PHOSfree and Algesides.

After coming here, I can assure you that most days I WILL not use the FAS-DPD because I do not need perfection. If I know my CYA is 40 ppm for example, I know I need 5 ppm of FC. If I keep it around 6 ppm FC, I have a safety margin, and why count so darned many drops with FAS-DPD daily?

I look at FAS-DPD as a troubleshooting test when EXACT numbers are needed.

Hence, I am buying this because it is a REASONABLE range for CYA < 100

What I am saying is that in addition to my K-2006 test kit, I am buying a K-1000 to get OTO (to check for the presence of chlorine), and a K-1001 to accurately check anything up to 5 ppm (Probably +/- 1 ppm), but I am getting that extra comparator that goes up to 10 ppm

2. ## Re: My Memorization Technique

Or just order the TF-100 that has more of the reagents you need, and includes the OTO test ... Which is a better deal. No real need for the DPD, the OTO will give you a good enough read daily and check with the FAS-DPD.

3. ## Re: My Memorization Technique

Where did you get the one that shows CL up to ten?

4. ## Re: My Memorization Technique

That's the 'new' comparator block. Taylor #9056

5. ## Re: My Memorization Technique

That seems more practical than the one I got from tfttestkits. Does tfttestkits sell that one? If not. How come?

6. ## Re: My Memorization Technique

That's the 'new' comparator block. Taylor #9056
Does this compartor use the same "red" reagent and 5 drops or is it differant?

7. ## Re: My Memorization Technique

Taylor is saying it's the same reagents and testing instructions. Just has more colors to pick from.

8. ## Re: My Memorization Technique

Taylor is saying it's the same reagents and testing instructions. Just has more colors to pick from.

I just bought this comparator last week (because I accidentally bought a large amount of R-0004 and realized I didn't have the right equipment to use it! I was having a time trying to find the instructions, but once I called Taylor they directed me to the right place. I don't know if you can use the reagents for the old comparator with this or how you'd do it, but here are the instructions for the new (#9056 or 2000) comparator:

9. ## Re: My Memorization Technique

One issue with the DPD test is that the color will fade out at high FC levels, you could think your FC is zero when in fact that FC is very high (has happened a few times on the forum). The OTO does not have that problem.

10. ## Re: My Memorization Technique

Right that has been said, but for everyday use With the right comparer DPD can test up to 10 ppm... Presuming your pool is well balanced the chlorine should not be outside the range of the comparer except when doing a SLAM or maybe after closing for the winter ...

never seen s scale for OTO above 5 ppm though it is obvious it supports oranges and Browns

11. ## Re: My Memorization Technique

Well, let us know how well you can differentiate the pinks.

12. ## Re: My Memorization Technique

I just ordered it to test it out. Will report back!

13. ## Re: My Memorization Technique

I just got my 2006 test kit. I have NEVER tested chlorine with the drop test before, but I like it a LOT more. I don't even have to mess around matching colors!

It is so much nicer.

14. ## Re: My Memorization Technique

This thread showed a big difference between the DPD and FAS-DPD, but it could have been a misinterpretation of the FAS-DPD test not counting each drop as 0.5 ppm. Nevertheless, we've had quite a few other reports of people reporting different values for DPD vs. FAS-DPD even though they were less than 10 so not getting bleached out. Color intensity/saturation comparisons can be tricky to do correctly. It's easier for a well-calibrated electronic device to do though inexpensive devices may not be much better than good vision.

Once you know your pool and mentally correlate an accurate FAS-DPD reading with a colorimetric test (DPD or OTO), then your quick daily checks could probably use either DPD or OTO.

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