I can't maintain chlorine in my IG vinyl pool

[Nysitemgr]

I am hopeful that some of the members of this forum can help me with this problem. I have owned my 26,000 gallon IG pool for 5 years, last season I had a problem maintaining chlorine in the pool during the spring time, the reason being high levels of nitrates which I addressed by draining (2 x) the pool about half way each time. I managed to reduce the nitrate level and thus had no further problems with chlorine. However, this year I have grown very frustrated as I have a similar condition but lowering the nitrate level to 10 by draining half way has not helped the situation. I am not sure what the cause of the nitrates is, but I can only guess lawn fertilizer from hurricane sandy this year and Irene last year. This year when I opened my pool, it took a little longer then usual to clear up the pool but I finally got it clear of algae. The pool water is clear and looks clean, but the chlorine dissipates after a few hours (and the outdoor temperature has only reached 80degrees thus far).

I have been going through shock at a high rate, using HTH Super shock (two 1 lb bags). I have taken water samples to the pool store, and the latest results are as follows:

TC: 2.5
FC: 2.5
TA: 140
PH: 7.5
Hardness: 180
Nitrate: 10 (down from 30 after draining)
Phosphate: 500

The results above we're the day after refilling and adding shock.

I have since noticed my chlorine disappearing after several hours after distributing throughout the pool. I was testing using 5 way test strips but yesterday I purchased a testing kit from Walmart. I found the following results:

TC: .5
BR: 1
TA: 140
PH: 7.2
Hardness: 240 ( added increaser after previous store results)
Nitrate: appears to be between 0 (30 second test), and 5 (60 second test), based on a test strip with two color tabs on it. Not sure how I should be reading this.
Phosphate: 1000 (I added phosph free immediately after the results)
The kit that I purchased does not have a test for free chlorine, so I also used the 5 way test strip and found near zero levels for both TC and FC.

I have read that a super chlorination to the breakpoint be necessary, just not sure what to do next. I have ordered the Taylor k2006 kit out of shear frustration. I purchased some HTH liquid chlorine (10%) and used 2 gallons last night to try to bring up the chlorine levels. The pool looks clean and clear, no algae in sight but worried about not having chlorine in pool for use of the pool.

Any help or advise would be greatly appreciated. Thanks

[Watermom]

The one number that you didn't supply (because your kit can measure it) is your CYA (cyanuric acid also called stabilizer) level. Without it, we can only guess at how to help. Hopefully your K-2006 will arrive soon and you can post a full set of numbers.

What has been your source of chlorine in the past? What are the ingredients in the HTH Super Shock?

Nitrates and phosphates seldom cause issues in pools contrary to what pool stores tell you. Selling products to remove them is big business, however, so they often emphasize those levels as being a huge problem.

Is this a liner pool or gunite?

You can ignore the bromine side of the tester you have; this is a chlorine pool.

Keep adding bleach a couple of times a day while you wait for that kit. As soon as we get some good numbers, especially a CYA reading, we can better advise you. Don't add anything else at this point but chlorine and Borax if your pH goes below 7.2.

Welcome to the Pool Forum!

[Nysitemgr]

My apologies for not including the cya info, the cya levels were at 30. However, I believe that they may be lower since the black dot at the bottom of the test tube never completely disappeared, it was slightly visible at the lowest reading at the top of the tube - line labeled 30. This was the lowest measurable "labeled" line on the test tube.

The latest results are below:

As of 9am this morning:

TC 10
FC 10
PH 7.2
TA 150
Hardness 250
CYA 30 (can still see the black dot, although very hazy)

I was originally using HTH sock n swim with a 62% calcium hyp concentration, I switched to HTH shock n swim with a 52% calcium hyp concentration. Yesterday morning I added 2 bags of the shock n swim only to have it go to near zero yesterday afternoon. Yesterday evening I added two gallons of HTH liquid chlorinator 10%. As of this morning I was pleasantly surprised to see that the chlorine levels are holding strong, a bit high but it is raining at the moment which I believe will help dilute.

My pool is vinyl 26,000 in ground.

Is bleach the same as the liquid chlorinator that I am using? Is this laundry type bleach that I can get at the supermarket?

Thanks

[PoolDoc]

1. As Watermom told you, stop worrying about nitrates and phosphates. They are NEVER 'the' problem. Sometimes they might contribute to 'the' problem, but if everything else is right, you probably won't have any problems with either nitrates or phosphates.

2. Stop using diluted chlorine products: compare by CHLORINE content, not chemical compound. Undiluted cal hypo will have a CHLORINE level of 65 - 75%. Pure dichlor will have a CHLORINE content of 55% - 62%; pure trichlor will have a CHLORINE content of ~88 - 90%

3. Compare bleach and liquid chlorine by comparing CHLORINE %; sodium hypochlorite (bleach) solutions of more than 9% can RAPIDLY deteriorate, if not fresh or if not kept cool.

4. If you have access to a Sams Club, they sell pure dichlor in a 24# box of bags or a 50# bucket of powder at an excellent price. Since you are low on CYA, and since dichlor adds BOTH chlorine and CYA, this would be a good option for you, for now. Do NOT buy from Walmat, Kmart, Costco, Lowes or Home Depot. When I last checked, those stores ALL sold diluted dichlor.

5. Get your K2006 and report levels ASAP.

6. Meanwhile use borax and muriatic acid (link in my signature) to keep pH between 7.2 and 7.8.

7. Do NOT worry about alkalinity or hardness -- do NOT add chemicals to adjust those.

[Nysitemgr]

Got it, hoping that my k2006 arrives in a few days. In the meantime below are my latest test results from the hth reagent test kit (have not added any chemicals since yesterday evening):

TC 5
FC 10 (the hth kit does not test for free chlorine, so for this result I am using a 6 way test strip that includes FC).
PH 7.5
TA 150
Hardness 250
CYA 30

Also, it has been raining all day raising the water level above skimmers, expected that the rain would dilute some of the results above.

[Watermom]

FYI: FC + CC = TC so, you have a mistake in your chlorine readings. Keeping my fingers crossed that your kit arrives for you soon! That will make things a lot easier for you.

[BigDave]

TC 5
FC 10 (the hth kit does not test for free chlorine, so for this result I am using a 6 way test strip ...This looks like a pretty good example of why we don't trust strips.
You will have a much easier go once you have the K-2006.

[Nysitemgr]

When things go bad, they really go bad. On Tuesday morning I found my pool pump not working, thought I would be spending $600 to $800 for a new one. Lucky, after some troubleshooting, I found that the pump motor had a bad capacitor, ordered it on Tuesday afternoon and received this morning. It has been replaced and my filtration system is back on line.

Now for some good news (I think), I performed a pool water test with my new Taylor K-2006 DPD Test kit and the results are below:

FC: 4
CC: .5
PH: 7.4
TA: 170
Total hardness: 330
CYA: 40

It appears like the pool has been holding chlorine, even though we have had a lot of rain in the area and my pump was out of service for several days. i have not added any chemicals and the water is clear. Are these levels within acceptable range?

Thanks to all for all of the great feedback,

[Watermom]

Since your CYA is at 40 (which is a good level), you probably should just use bleach instead of dichlor.

Is this a liner pool or gunite?

[Nysitemgr]

Liner pool, I still have 8 new gallons of the hth liquid chlorinator, should I return and just get the bleach?

[PoolDoc]

"liquid chlorinator" is just 10 - 12% bleach.