# Thread: Possible formula to estimate reagent usage

1. ## Possible formula to estimate reagent usage

As a user of TF kit FAS/DPD and needing some lead time to import it from USA ( Dave ), I been trying to figure out how long will a bottle of R-00871 last. The R-0870 podwer is not an issue. Shocking a pool will take lots of R-0871 anyway.

I can't get an exact figure because I do not know the surface tension, specif gravity and whatever the figure needed to calculate how many milliliters is a drop of reagent R-0871. As if I can calculate if I know those numbers..LOL

The common rule of thumb I got is 0.04ml (25 drops per 1 ml ) per drop or 20 drops per 1 ml. This is for water or common solvent from an eye dropper. I will use 20 drops per milliliter.
The R-00871 is 30 ml, that means 600 drops.

So based on 0.5 PPM test resolution and no CC, one test a day and no shocking.... this is what to expect :

1.5 PPM FC = 200 test 6.6 months
2.0 PPM FC = 150 test 5 months
2.5 PPM FC = 120 test 4 months
3.0 PPM FC = 100 test 3.3 months
3.5 PPM FC = 85 test 2.8 months

So for me, I will use two months as maximum because I do usually two test a day.

I am already about to deplet my R-0871 in only a bit over 2 weeks... ...oh Boy, I am "shocked" to have done so many "shocking" in such a "shocking-ly" short period of time... :P

So those of you living outside USA, you can plan ahead.
I have now 2 more bottles of R-0871 and R-0870 powder ordered as spare, but only 1 of R-003 original to the complete test kit.

Just so that you guys know, how cheap our dear Dave ( Duraleigh ) is selling here is the calculation :

For US\$ 23 you get ....
2 x 30ml R-0871 ( total 60ml )
1 x 22ml R-003
1 x 10 grams DPD powder

Taylor direct for the kit but much less R-0871 reagent at only 22 ml and they are US\$24
Poolcenter.com is asking US\$21.97 for Taylor kit.
The only extra thing you got from Taylor is the blue box. I don't need the box.

The way I see it, you will run out of R-0871 first, so a 22ml Taylor is so wasteful...but you get the box..

If I want to calculate \$\$ for \$\$, this is how I will calculate.
I get 60ml + 22 ml + 10 gram = US\$23 from TF test kit
I get 22ml + 22ml + 10 gram = US\$21.97 from Taylor/Poolcenter.com

So per unit of either milliliters or grams =
92 units for US\$23 by TF kit
54 units for US\$21.87 by Taylor/Poolcenter.com

Simply put, TF kit is almost half the price of Taylor kit or Taylor kit is almost double the TF kit.
If you shock a lot, Taylor kit can be 22/60ml = 2.7 times more expensive than a TF kit because I looked at Taylor website and they do not sell R-0871 individually. It must come as test kit....

So, thank you Dave ( Duraleigh )...you are not only a Speedy Gonzales on delivery, I also doubt selling the TF kit can do you any financial justice worth the time. If you can sell 500 kits a day...maybe I want to be you.... , otherwise I want to be your customer.

2. ## Re: Possible formula to estimate reagent usage

WOW! What a post, SPP! Actually, I was wondering most of that info myself. So I thank you for taking it upon yourself to figure all this out. I will print it out and put it in my pool folder!

Have a great Labor Day today!!

3. ## Re: Possible formula to estimate reagent usage

Gee...holiday for u guys there ??? Nice...have fun Cherie. Now wonder so quiet today.

I got to work....

4. ## Re: Possible formula to estimate reagent usage

OOPS! So sorry about that!! I forgot the country designation. But yes, although it's been duly noted that those in America receive the least vacation days of any industrialized nation in the world, they are "nice enough" to let us have a Labor Day vacation day!

We'll have some fun for you too...in the pool!

5. ## Re: Possible formula to estimate reagent usage

For my reagent tips I get roughly 24-26 drops per ml. I think your 20 drops per ml is on the low side. So you are probably using up reagents a little slower than you calculated. Even so, as you point out, Dave's refill prices are a very good deal.

6. ## Re: Possible formula to estimate reagent usage

Yipeee !!!!! 24 drops !!!! That means Dave kit is even cheaper now..... :P :P...Yeah Baby !!!

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