Become a TFP Supporter Pool Math Forum Rules Pool School
Results 1 to 15 of 15

Thread: DPD powder. How many tests?

  1. Back To Top    #1

    DPD powder. How many tests?

    How many tests can be run with the 10g of DPD powder that is commonly sold?

  2. Back To Top    #2
    Guest
    I'm into my second year already and the container is almost half full. Depends on how often you test. DPD powder does go bad. Light, heat, and moisture are it's enemies. I keep my reserve of DPD powder in a container that I vacuum seal in a small bag (who ever thought that a Foodsaver would be good for pool chemicals?) and only have one open at a time.

  3. Back To Top    #3
    So, how many tests have you run with the 5g you used?


  4. Back To Top    #4
    Guest
    I usually test weekly with the FAS-DPD test and use either OTO or strips in between for quick checks.

  5. Back To Top    #5
    52 tests per year from 5g worth of DPD powder?

    I'm looking for "10g of DPD powder will do X tests at two scoops per test".

    Spill the beans, man...

  6. Back To Top    #6

    Join Date
    May 2007
    Location
    Houston, Texas, USA
    Posts
    148
    Quote Originally Posted by Rangeball
    52 tests per year from 5g worth of DPD powder?

    I'm looking for "10g of DPD powder will do X tests at two scoops per test".

    Spill the beans, man...
    Not asking for much are ya? I have tested *about* 90 times and still have enough left for at least 10 more tests.
    Poor Man's Pool
    Doughboy 18 ft round above ground
    7600 gal with center drain
    Pentair sand filter, 1 HP pump
    50 ppm borates
    "I know just enough to be dangerous"
    Pool Calc Ver 1.41 (Excel)

  7. Back To Top    #7
    Guest
    Quote Originally Posted by Rangeball
    52 tests per year from 5g worth of DPD powder?

    I'm looking for "10g of DPD powder will do X tests at two scoops per test".

    Spill the beans, man...
    Easy way for you to find out. Measure out the 2 scoops of DPD powder and weigh it on triple beam balance. Dived the 10 grams by the amount you weighed and you should have an idea of how many tests. The trick is you have to measure the scoop out exactly the same way each time. (Or just weight the correct amount you need each time on the triple beam.) Also realize that if you are testing very high chlorine levels you might need more than 2 scoops of DPD powder to overcome the bleaching effects of very high chlorine on the Wurster dye that forms when it combines with the chlorine (this is the red color you see.)

    Based on my own and Poseiden's results I would say you get in the neighborhoold of 100 tests out of 10 grams but it really does depend on how accurately you measure with the scoop, how much you spill, and how high the chlorine level is that you are testing. It's almost like asking how many tests can you get from the titrant in the test. There is really no way to tell since that will depend on how many dropsy you use in each test and that will depend on your chlorine level which most likely will be different each time you test.

  8. Back To Top    #8
    I figured it'd be an easy questions, given that you are taking a known quantity per test from a known quantity Are you using one or two scoops per test?

    Thanks

  9. Back To Top    #9
    Guest
    2 scopps using either Taylor or TF teskit scoops. I scoop when using PooSolutions PS-234 which has a bigger scoop.

  10. Back To Top    #10
    I only see one flaw in your logic. It assumes I have the powder to measure

    I'm trying to figure out how much to order. Since it's cheap, I thought I'd get 2 10g bottles if needed. Doesn't sound like it's needed.

    Thanks a bunch

  11. Back To Top    #11
    Waterbear, you mentioned needing more DPD powder with high chlorine. My dad's pool is in double digits due to very high CYA.

    Do you simply keep adding scoops until you get a red or pink color? How do you know when to stop, when a certain color intensitiy is reached?

  12. Back To Top    #12
    Range,

    I'm not going to be much more help but I typically go through (2) 10g bottles in a season and I test at least every other day, usually daily. I prefer the DPD as the OTO test are pretty much guessing to me. What I do is buy them two at a time, then pour as much of one into the other until it is full, then refill my "working" container as needed. This keeps the DPD fresh.

    Dave

  13. Back To Top    #13
    Guest
    Quote Originally Posted by Rangeball
    Waterbear, you mentioned needing more DPD powder with high chlorine. My dad's pool is in double digits due to very high CYA.

    Do you simply keep adding scoops until you get a red or pink color? How do you know when to stop, when a certain color intensitiy is reached?
    IF the normal amount of DPD bleaches out then add it a scoopful at a time until a stable color is reached. This will not normally be needed unless chlorine levels are VERY high, perhaps over 20-25 ppm.

  14. Back To Top    #14
    gonefishin's Avatar
    Join Date
    Apr 2007
    Location
    Joliet, Il.
    Posts
    411
    Quote Originally Posted by Rangeball
    I only see one flaw in your logic. It assumes I have the powder to measure

    I'm trying to figure out how much to order. Since it's cheap, I thought I'd get 2 10g bottles if needed. Doesn't sound like it's needed.

    Thanks a bunch
    Hi Rangeball,

    Myself...I would treat it like I do spices for cooking. Order enough to get me through six months or a little more. Then place another order of fresh spices once the old bottle is low.

    but that's me
    dan
    33' Aqua-Leader AGP
    Hayward cartridge filter and IntelliFlo VS pump.
    Solar Heat coming ; used to own Aqua-Cal HeatWave 100k (HeatPump)
    Aqua-Rite t-15 SWG

  15. Back To Top    #15
    Thanks all. Stuffs been ordered. From Dave of course

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •