Pool Store Takeover - High CYA

[ddrager]

We purchased our house last summer and only had the pool open for about a month. This is my first experience with a pool of any sort, so I had the pool company over to 'show me the ropes'. Basically, they had me replacing the trichlor pucks and backwashing occasionally.

Towards the end of the summer (pool season is 4 months here) the pool started to eat through Chlorine [tri-chlor granules] ... crazy amounts. We figured something was up but it was time to close the pool. CYA showed high on the test strips but the pool company said not to be concerned about CYA.

Of course, I joined TFP over the winter and have been reading up on what could have caused the Chlorine consumption. I purchased a Taylor kit and CYA was off the charts. Before opening the pool this year I decided to drain it out and fill it - I would estimate I did about a 50% drain.

After opening it (I had them 'shock' it too - they used liquid chlorine) I finally have my first full readings:

FC: 7.2
PH: 7.8
TA: 260
CYA: 320

Yes, 320! No wonder it was eating Chlorine for breakfast.

I think the only option at this point is to drain it and refill again. At 320 PoolMath says to drain about 80%. Here are my questions:

- Is it safe to drain down to 20%? Inground plaster pool, ~ 22000 gal
- We are planning a memorial day party (5 days) - my plan is to do the draining after that. Assuming we keep up with Chlorine until then, is it safe to swim in with the high CYA?
- I will measure CYA again to confirm that number as I expect it is so high to be 'off the charts', but does shocking the pool cause CYA to be inaccurate?

Thanks for your help, I plan to stick around here to help others escape the chemical peddlers' grips!

 

[jblizzle]

Welcome to TFP!!!

1. Depends on how high your ground water table is.
2. We say it is safe to swim when you can see the bottom and the FC is between the minimum and the shock level for your CYA level. According to PoolMath, the minimum FC for a CYA level that high is 24ppm (and shock level is 126ppm ) ... although you are WAY outside the realm of normality.
3. How did you get the level of 320ppm? Only low water temps and improper lighting affect the CYA test.

BTW, we do not "shock" pools, we follow the ShockLevelAndMAINTAIN Process.

Also, it is not the high CYA that is "eating the chlorine" in fact a high CYA level should protect the FC from the sun better. You ware loosing all your FC to something that is growing in your pool since you are not maintaining a high enough FC level for that CYA level. Like I said above, the MINIMUM FC you should ever have would be 24ppm. But that is just not realistic and you need to replace water.

 

[Azgirl71]

Welcome to TFP and congrats on your test kit! That is some high CYA. With a plaster pool I am not aware of any damage that could be caused by draining to 20%. Someone else will be able to confirm though. CYA test is not affected by high FC. You just want to make sure the water is at least 70* or higher when you test CYA.

 

[borjis]

If you have high CYA the chlorine goes away slower...it's a stabilizer. It's possible the chlorine was getting burned off by sun or
something else..but the high CYA wouldn't be causing that.

It's fine to be swimming at that level...there are tons of neglected pools with much higher levels.

When I do partial drains, just for safety sake, I drain down to just below the returns (winterize levels) then refill after.

I did that a total of 3 times and it got my cya from 300+ to around 120.

 

[ddrager]

Thanks for quick replies, you all rock!

Welcome to TFP!!!

1. Depends on how high your ground water table is.
2. We say it is safe to swim when you can see the bottom and the FC is between the minimum and the shock level for your CYA level. According to PoolMath, the minimum FC for a CYA level that high is 24ppm (and shock level is 126ppm ) ... although you are WAY outside the realm of normality.
3. How did you get the level of 320ppm? Only low water temps and improper lighting affect the CYA test.

BTW, we do not "shock" pools, we follow the ShockLevelAndMAINTAIN Process.

1. Hard for me to say - we have had some thunderstorms lately - will wait for a few days without rain to drain it to that level.
2. I agree - CYA number is absolutely crazy.
3. Did the test, way below 100 - halved the water and put in half tap water - still below the 100 threshhold - diluted again - looked to be about 80. Multiply that by 4 to get 320. I do have low water temp right now and did the test indoors - perhaps it would be better to do it in full sunlight to make sure I am reading correct levels.

Welcome to TFP and congrats on your test kit! That is some high CYA. With a plaster pool I am not aware of any damage that could be caused by draining to 20%. Someone else will be able to confirm though. CYA test is not affected by high FC. You just want to make sure the water is at least 70* or higher when you test CYA.

It is a bit cold right now, I will get an exact measurement tonight.

After reading some threads, it sounds like I should allow the water to warm up to room temp before doing the test, so I will do that again to get a better measurement. I'm sure CYA is high but perhaps not *that* high.

Thanks again!

 

[Isaac-1]

You might be a bit off indoors, but not enough to matter in this case

 

[borjis]

make sure when you test the CYA in the black dot tube, that the full sun is to your back and the
cya tube is at waist level being in your shadow.

That's the most reliable way to get a fairly accurate reading.

if the tube is exposed to full sunlight it will read your CYA much lower than it actually is.

 

[duraleigh]

The variables of lighting on the CYA test are not enough to make much difference in your case.

The biggest issue you have is dilution of the test which makes the test pretty inaccurate.

Assuming your water table is reasonably low (it should be in PA) you should be quite safe with a 75% drain, refill and then test. You may need to drain a bit more or possible even add back but that should be a safe transition.

 

[ddrager]

Again will do a 75% drain/refill after our Memorial Day party, just trying to get it safe for guests for now

Testing again this afternoon with proper temp/lighting:

CYA: 320
FC: 5
CC: 7
pH: 7.7

According to the CYA/Chlorine chart and Poolmath it says I should be aiming for 24. That's obviously way too high Am I OK keeping it around 5-7 for now? The pool has really cleared up and looks swimmable. I am being very aggressive with backwashing the DE Filter.

Also strangely, when I try to test with a strip (just for comparison) it gives the following results:

TC: 5
FC: 0

That is a bit worrisome that it is reading FC as 0. Is that because my CYA is so high?

Thanks for the input all!

 

[jblizzle]

Technically no, the pool is not safe at a FC level of 5-7ppm because it is below the minimum for you CYA.

And a CC of 7 is not good either since it should be 0. ... and that almost jives with the test strip.

I would not let anyone swim in this pool if it were mine.

 

[ddrager]

Technically no, the pool is not safe at a FC level of 5-7ppm because it is below the minimum for you CYA.

And a CC of 7 is not good either since it should be 0. ... and that almost jives with the test strip.

I would not let anyone swim in this pool if it were mine.

You plus others have convinced me it is probably best to drain/fill pool before the party - I should have enough time. I'll begin that process, then add liquid chlorine to bring up FC levels. I expect CYA won't be in 'ideal' range but if I can bring it down to 90/100 at least it is manageable. Thank you for feedback all!

 

[pooldv]

Agreed, good call!

 

[kimkats]

For the best-------your guests and your wallet!

Good job getting a good test kit. When you get your levels balanced you will see how easy your pool will be to care for.

Kim

 

[Pogueld]

Congrats on getting started with TFP! You will be glad you did even though it seems like a headache in the first place. Knowledge is power.


Sent from my iPhone using Tapatalk

 

[ddrager]

The pool is about 30-40% drained so I am well on my way, I should begin to refill this afternoon.

What is the process for adding Chlorine back into the pool? My tentative plan is to get a case or ~ 3 bottles of Great Value 128oz bleach from Walmart, according to pool calc I will need around 1.5-2 jugs to bring the Chlorine up (depending on my CYA level at end of refill).

Sound about right?

Can I start adding these as soon as I begin the refill? Or better to wait until the pool is fuller?

 

[tim5055]

If you are going to add before the pool is at a level the pump can run, be sure to pour it in the stream of water being added so it mixes as well as possible. I would add some myself, but no where near the full amount until the pump is running.


Following my habits, I never buy less than 8 - 10 bottles. The don't go bad that quick and I know I will use them.

 

[ddrager]

Getting nervous about draining the pool - do I need to open the hydrostatic valves or are they 'automatic'? I have 3 total, 2 in deep end.

It is raining lightly but generally has been dry here in SE PA. Pool is at top of hilly area so I think water table will be good, but really hard to say for sure.

 

[kimkats]

You know what? You can do little drains to be on the really safe side.

With it being a plaster pool you have more weight than say a fiberglass so you should be able to take out more without the worry.

BUT what can your "worry" take? For me I like baby steps.

Do what makes you have less worry. There is no price for a worry free gut!

I love your pool! Those dolphins are outstanding and the step accents are neat!

Kim

 

[ddrager]

You know what? You can do little drains to be on the really safe side.

With it being a plaster pool you have more weight than say a fiberglass so you should be able to take out more without the worry.

BUT what can your "worry" take? For me I like baby steps.

Do what makes you have less worry. There is no price for a worry free gut!

I love your pool! Those dolphins are outstanding and the step accents are neat!

Kim

Thanks, I credit the previous owner who installed it, he had a great sense of style!

I agree with what you are saying, once I get home today I am going to drain from the deep and and start refilling from the shallow end - which should almost be empty. I'll let that run another day (assuming they are at about stasis) and then refill the pool. Just hoping I have enough time to complete before Memorial Day!

 

[borjis]

There's an area in the hills near where I live that actually has a very high water table even though its higher elevation. fyi.

I would just drain down to just under your returns (as the photo shows) then refill, run the pump 8 hours, then drain down
again. Doing this 3 to 4 times should get your cya around 100 ish. (at least it did on my 17k gallon pool)

Love the Dolphins!