Pool Math not working for me???

[Russmd]

I just drained, blasted, and refilled my 30,000 gal plaster salt pool. Cleaned all the grids. I haven't added salt yet. Our water here is very alkaline and high in minerals, I drained to lower the calcium.

I enter the test values in Pool Math:
30,000 gal plaster
FC 0 with target 4 - it tells me 128 oz (1 gal) 12% bleach.
pH 8 with target 7.6, TAlk 200 with target 60 - it tells me 1 gal 14.5% muriatic acid.
CA 300 CYA 0

I added both of those bleach (12% pool grade) and acid amounts, good new chemicals, and got a negligeable bump in both numbers. FCl went to 0.5, pH didn't move. By previous experience, I knew one bottle of acid wasn't going to do anything.

There was no stabilizer in yet, I just added 2 pounds (I like to go up slowly so as not to overdo it). Is that true that I'll need to add 160oz (10lbs) of stabilizer to get it from zero to 40?

What am I doing wrong? Why are my pool Math numbers so far off?

Thanks,
Russ

 

[domct203]

I just drained, blasted, and refilled my 30,000 gal plaster salt pool. Cleaned all the grids. I haven't added salt yet. Our water here is very alkaline and high in minerals, I drained to lower the calcium.

I enter the test values in Pool Math:
30,000 gal plaster
FC 0 with target 4 - it tells me 128 oz (1 gal) 12% bleach.
pH 8 with target 7.6, TAlk 200 with target 60 - it tells me 1 gal 14.5% muriatic acid.
CA 300 CYA 0

I added both of those bleach (12% pool grade) and acid amounts, good new chemicals, and got a negligeable bump in both numbers. FCl went to 0.5, pH didn't move. By previous experience, I knew one bottle of acid wasn't going to do anything.

There was no stabilizer in yet, I just added 2 pounds (I like to go up slowly so as not to overdo it). Is that true that I'll need to add 160oz (10lbs) of stabilizer to get it from zero to 40?

What am I doing wrong? Why are my pool Math numbers so far off?

Thanks,
Russ

I get the same Pool Math results as you, and as a sanity check I entered my own pool's volume and the results are correct, so I think it's safe to say the issue here is not Pool Math.

How old are your K2006's reagents?

 

[Bama Rambler]

How long did you wait between adding the chems and retesting?

You could have some organics in that new water that burned off the FC as soon as you added it.

You're TA could also be higher than you tested.

 

[Russmd]

Thanks for the responses. My reagents are not more than 9 months old, and I have two different test kits that gave me similar results. I tested 24 hours after adding the chemicals, pump running continuously. I'd be surprised about organics as the pool was acid washed, then refilled over 72 hours. Temp has been below 65 here and cloudy. But, could be...

What about the stabilizer question- does 10 lbs make sense?
From what I've read, adding stabilizer should lower pH. Should I get the CYA right before adding more acid?
I agree TAlk may be higher than the result.
Should I also wait until stabilizer is right before adding more chlorine?

 

[JoyfulNoise]

Do you have the acid-demand reagent, R-0005? If so, you can use it to roughly tell you how much acid to add to get to the desired pH color you're looking for. Pool Math calculates the same acid addition based on the chemical parameters you input but if something is a little off in your analysis, then the amount of acid needed can be off too. In the case of the acid demand drops, you are measuring your pool water exactly as it is and so it can give you confidence that the numbers you're putting into PoolMath are close.

With alkalinity as high as yours and what amounts to new plaster surface, the addition of the CYA is not going to have much measurable effect on the pH so I would not worry about it in that sense. Just go ahead and start hanging socks of CYA in the pool and let them dissolve. If you convert 10lbs of CYA to milligrams and your pool volume to liters and divide the two then you get 39.9 mg/L which is 39.9 ppm. So yes, 10 pounds of CYA makes sense.

 

[Russmd]

Thank you. I do have the reagent and will check the acid demand.
Russ

 

[stodds]

I know I'm new here. But, if you waited 24 hours between chem add and retest, I would think that the chlorine loss of 3.5 ppm in a 24-hour period is not all that surprising. Assuming, that is, you had a sunny day with no CYA.

 

[Russmd]

I guess I'm not following. When the FCl reads 4 on the test scale, is that ppm (I'm not sure of the units). If it is, there's no way a loss of 3.5 per day could be possible. That would mean we'd have to add chlorine every day. Am I off on the units?

 

[stodds]

Yes. It is measured in ppm. Read up on CYA. It protects your chlorine from being burned off quickly by the sun, in simple terms. This article: Predicting the rate of chlorine loss based on CYA levels is over my head. But, look at the last post. The last chart (which is for 10ppm CYA -- more than you had) shows 10 ppm of chlorine disappearing in 4 hours of sunlight. So 3.5 in 24 hours seems plausible for sure.

 

[pooldv]

Normal FC usage in a pool during swim season is 2-4 ppm per day. When water drops below 60 degrees it drops off quite a bit. Yes, it is measuring PPM. Yes, chlorine generally needs to be added daily during summer and every few days during winter.

 

[JoyfulNoise]

I guess I'm not following. When the FCl reads 4 on the test scale, is that ppm (I'm not sure of the units). If it is, there's no way a loss of 3.5 per day could be possible. That would mean we'd have to add chlorine every day. Am I off on the units?

What do you mean when you say the FC "reads 4 on the test scale."? Your signature says you have a K-2006 which uses the DPD-FAS titration chemistry to give you a drop count based determination of FC, not a color read. Are you using some kind of quick tester to read FC? If so, which one are you using.

You may not notice the drop in FC because you are using an SWG to generate chlorine throughout the day. But, if you take the pump run time and the fractional amount of time that the SWG is set to be on for and multiply that by the production rate for your AquaPure cell (~1.25lbs per 24 hours), then you'd probably see anywhere form a 2-4ppm daily loss rate.

 

[Russmd]

Yes, I was just using one of my quick testers to measure chlorine. I used my k2006 today ( I added more bleach yesterday), and am at 6 so all's good there. I've not added salt yet, SWG is off. pH is 7.6, TAlk is 200. I'm adding more acid to 7.2 and will aerate. Calcium is 300. CYA is slightly under 30 after 5 lbs dissolved. Adding slowly to goal of 70. Do you wait for the black dot to completely disappear or just mostly? Thanks.

 

[JoyfulNoise]

If the tester is a yellow shade (OTO chemistry), be very careful with those as I have found them to be highly inaccurate. I never use them as it did not matter if the TC was 2,3,4,5 or 6ppm, they all gave the same color yellow. It wasn't until the TC was well over 10ppm that it would even begin to turn a shade of orange. I threw that tester right in the trash after I got my K-2006.

If you want a daily spot tester that actually works, get a K-1001. It's based on the DPD chemistry and the shades of pink very accurately match the color swatches in the tester block. I use my K-1001 all the time.

As for CYA testing, here are the tips -

1. Bright, sunny outdoor lighting is a must
2. Back to the sun with the tube held waste high
3. Keep BOTH EYES open
4. Look away and don't intently stare at the tube. I like to fill it up 10ppm at a time and then view the dot.
5. Hold the tube or comparator block so that your fingers are not blocking or obscuring the entry of light in anyway through the sides of the tube
6. Water sample temp must be greater than 68F
7. Repeat the test several times and take an average, round answer UP to the nearest 10ppm

See this website for how to know when the dot has "disappeared" - http://taylortechnologies.com/ChemistryTopicsCM.ASP?ContentID=36

 

[pooldv]

By repeat the test it is meant to pour the solution back and forth as many times as needed in vatious light to feel comfortable with your result. No need to mix up a new test sample.

 

[miles267]

Is it the K-1001-24 for pool and spa with 3 reagents?


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[pooldv]

Yes, the k-1001 is the DPD chlorine test. But, I prefer to use the 9056 comparator block because it reads FC up to 10 ppm rather than 5 ppm. I bought mine separately and then bought the r-0001c, r-0002c and r-0014c reagents in 2 oz bottles.

 

[JoyfulNoise]

Is it the K-1001-24 for pool and spa with 3 reagents?


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That part number indicates a 24-pack pallet. Unless you want 24 copies of K-1001, I'd loom for a different p/n

Yes, three reagents - R-0001, R-0002 & R-0014 as well as a midget comparator block.

The R-0014 is the phenol red pH test that is compatible with the midget comparator block. It's is a less concentrated version of the R-0004 reagent. It can not be used with a high-range comparator block found in the K-2006.


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