Bad DPD Powder?

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TFPNoobie

TFPNoobie

Well-known member
Aug 5, 2020
83
Jamison, PA
Pool Size
12000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-20
What the heck am I doing wrong. First time ever testing a newly installed pool. Last week the builder added shock. I bought a K-2006 from Home Depot's website and the pH is at 8.0 so no issues with testing that.

However, I'm doing the DPD test and I add water to the 25mL line. I add 2 scoops of DPD powder and nothing. I swirl it and it's very clumpy in the tube. I keep swirling it for a few minutes still clumpy and clear water. Instructions say to keep adding until water turns pink. Well, I've added 10 scoops and it's still clear. Am I doing something wrong here?
 
mknauss said:
That is long gone. Chlorine must be added daily.

No need to use a 25 ml sample. Use a 10 ml sample. One scoop of powder. If not pink, FC = 0.
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Does that mean the SWG isn't really adding any consequential amount of chlorine?

So add 1lb of shock? Run the pump for 24 hours then test again?

Supposed to be 82 on Sunday and my son was hoping to be able to go in it. Not sure i'll be chemically balanced in time.

Thank you.
 
mknauss said:
What is it set to generate each day? Is your water warm enough for it to generate?
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I just turned the heater on this morning because we're supposed to be getting some warmer weather. The SWG was too cold this morning but it's generating now and I have it set to 80%. Water temp on heater indicates about 58.
 

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Jimrahbe said:
T,

Your cell will make .23 ppm of FC per hour at 80%.. To make 3 ppm of FC will take about 13 hours.

What were you expecting???

How long do you run the pump and cell each day?

Jim R.
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I don't know what I was expecting. PB added shock last week and haven't heard anything from them since. I guess I figured that would raise FC enough then the SWG would maintain. I'm learning now how much FC the SWG will produce which is new info to me. PB initially had the pump set to run from 10-6 but I changed it 2 days ago to run from 10-8. Maybe I should do 10-10.

And they had the SWG on 60% until about 2 days ago so I changed it to 80%. Now at 100%.
 
TFPNoobie said:
I swirl it
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Get a SpeedStir. It will make your testing much better, faster, and easier.


TFPNoobie said:
Instructions say to keep adding until water turns pink.
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The test assumes you have chlorine in the water. If the sample stays clear, you have no chlorine.

TFPNoobie said:
Does that mean the SWG isn't really adding any consequential amount of chlorine?
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Ideally, you should have a SWG that's rated for at least twice your volume. In your case, an IC40 would be a better option. With your IC20, you'll need to run your pump much longer. There's a SWG calculator in PoolMath.
 
Nice to meet you via TFP :)

I strongly recommend adding liquid chlorine to achieve your target FC level, and then use the saltwater chlorine generator to maintain your target level.

To determine the FC target level, you must first test your CYA level (aka stabiliser, cyanuric acid) and then find your FC target from this chart: FC/CYA Levels

If you already have enough CYA, don't add dry chlorine products. If you need to raise CYA, it's fine to do so with dry chlorine products, but also keep track of how much CYA you're adding. Most dry chlorine products contain CYA, but not all, so check the label. If what you call "shock" is calcium hypochlorite, it does not contain CYA. If it's dichlor (sometimes called granular shock) it does contain CYA. The CYA is persistent, whereas the chlorine is exhausted and must be replenished if the level is low.

After you've achieved your target level, it would be a good idea to do an overnight chlorine loss test, just to be sure the water is free of algae. Overnight Chlorine Loss Test
 
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Couple things. I’m guessing you have no CYA. PB left me some but I didn’t know what it was and I couldn’t figure out where all the chlorine was going. Confirm your CYA. I had a chlorine reading of 12 one morning and by afternoon I was back down to almost zero. You have to have CYA.

I’m also guessing you have one of those simple test kits where it has two tubes, one for chlorine and one for pH - where you add five drops to each side. If you don’t, get one. Turn your SWG on 100% and then take a water sample right at one of your jets. Doesn’t matter what the chlorine level is, your just trying to see if you’re generating chlorine. In the simple test kit, it should show a pretty dark yellow, but the main thing is to confirm that there is some - i.e., your SWG is working. Then, once you’ve confirmed that your getting chlorine, get some water from that same place and try the test with the DPD powder. Again, the chlorine reading won’t be correct, but you’ll be able to see if your powder is detecting chlorine.

Good luck.
 
Last edited:
I am going to go back a bit to make sure the basic pool care is covered:
Pool care links:
Print these out:
Pool School - Basic Pool Care Schedule
Pool School - Recommended Levels

Bookmark these:
Pool School - Recommended Pool Chemicals
Trouble Free Pool
Pool School - ABCs of Pool Water Chemistry

Please note the one called Basic Pool Care Schedule. This one is very important to follow especially in the beginning of learning what your pool needs. As you get to know your pool's needs you will find you don't need to test and such as often. In the beginning you will need to.

As you are finding out your SWG is not good at getting the FC level up. To do so you need some liquid chlorine to get the FC level up. The SWG will hold it from there IF there is enough CYA to buffer the sun taking the FC.

Note one of the links is to Pool Math. That is VERY helpful to tell you how much of something you need to reach your goal.

Good luck and let us know how we can help!

Kim:kim:
 
As others have said, if you're at 0 chlorine, add liquid chlorine to get to desired level and let th SWG maintain. If SWG can't "keep up" don't blame the SWG right away. That's more often a sign that something in your pool is using up your chlorine fast. The recommendation in that case is a SLAM.
 
Did you get any sort of pool school with your builder? Mine was useless sounds like yours was also.

In PA your heat pump isn't going to do much with the temps this time of year. Without a solar cover (bubble cover) you will lose more at night than the heat pump adds during the day. I don't think there is any chance to get your pool up to swimming temp. It needs to be at least like 80 to make it bearable. You also should be testing your chlorine level daily until you know your pool better. Keep a supply of bleach (chlorine) on hand.
 
@TFPNoobie
I know you’ve been given alot of info & advice.
For us To give the most accurate guidance do all the tests w/ your k2006
& post them here like this
Fc
Cc
Ph
Ta
Cya
Ch
Salt
 

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