High CYA, afraid of liner damage draining water...

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I

indyducati

0
Jul 20, 2013
5
Indianapolis IN
Hello folks,

I'm a lurker, posting for the first time.

We've been in this house for 5 years. I think the IG pool is 8-10yo. For the past three years I've done everything except closing myself.
I've used our local store for tests and chemicals. I've fought PH and FC and algae every week.

Some pool info; IG, 25000 gal., vinyl liner,
The water looks great. The kids wear googles, no one complains yet of irritated eyes.

Today my Taylor K-2006 kit arrived. I've read Pool School, still don't really understand much :)

If my tests are correct, these numbers seem wacky...

FC 1.5
CC 1.5
TA 40
CH 250
CYA +100

It looks like I need to drain and replace 60% of the water ?

Our liner is very wrinkled, pulling away from the corners. I know we're due for a liner replacement.
I was hoping to delay the liner for another season or two. I'm afraid of totally ruining the liner if I do a
big drain and refill all at once. Backwashing / draining a couple inches a week and refilling from our well seems
safer for the liner. Although I hate adding well water, it's hard and has high iron.

I've never seen a real 'order of operations', as far as finding balanced water.
Should my priority belowering the CYA or raising the PH ?
I've many questions I'll save for later.

Thank you,
Steve
 
It's probably roughly correct. The effects section in PoolMath makes some assumption. You have to remember that pH is a logarithmic scale. Going from 6.0 to 7.5 represents one and half orders of magnitude change.

So, unless you really really sure about your numbers, I would proceed slowly. Assume your starting point is 6.8 and your target is 7.5. Add what pool math says. If after adding it you're still not in the measurable pH range, add the same amount again. Keep that up until you see the color in the right range.

Since your TA is fairly low, you can use soda ash (washing soda) to raise both pH and TA together but I would be more careful with that and use TA to guide that amount because you don't want to spike your TA up past 100ppm.


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I was just about to post about 40 pounds when Matt chimed-in. :) But Steve, I have other concerns and just have to make sure you consider everything okay.
- Ideally we drain/exchange water first to control CYA. That's for algae control with FC. You can still confirm (or try to) your true CYA with the diluted test method. From there we would ideally do water exchanges so you don't pour chemicals right out onto the lawn and waste money. Once you have that CYA back under control, then you would adjust all the levels as required. If the small/multiple water exchanges are your only choice based on the age of liner, then just understand some effort will "go down the lawn". :)
- The more you refill with the well (iron) the more chance you have of a chemical reaction between iron and chlorine. If your CYA remains high, your FC must also be high to compensate, therefore there's more chance of color change/staining. With an older liner it may not be a big deal for you, but I want you to know. You may also want to have some sequestrants available once the water exchanges are complete.

You're in a bit of a pickle there with several things to consider, not just pH, so you've got a few things to consider at once. Let us know if you have any questions.
 

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Be cautious adding that much to get your ph up.....you might get some awful metal staining if you do it too quick.

I had the same ph when I got my first house with a pool. It too had very high cya and the previous owner used copper
algecide, so I added all the ph up over 3 days and had metal stains shortly after.

In hindsight I should (and ended up) have just done the water replacement, it would have taken care of all the issues
without unsightly metal stains.


If you get all the chemistry in order, who knows you might get a few more years out of your liner.

The liner I had replaced in my new home had lasted 22 years before it fell apart and the previous owners used tabs in a feeder.
 
Welp...

Last night I added 6lb of Borax and 1" of water to the pool. Pumps runs 24x7.

This morning I tested again. I used "50%tap+50% pool x 2" for the CYA test.

FC 1.4
CC 1.0
PH <7
TA 50
CH 260
CYA 120

I'll add four more pounds of Borax this afternoon.

I really appreciate all of your interest.
Thanks,
Steve
 
I'd do a couple drain/refill cycles before adding anything, you'd just waste it otherwise. Don't drain past the bottom step, or leave 1 ft in the shallow end.
 
I had the same thing happened two years ago. Draining the pool water was not an option for me - too costly. It was also in early August. So what I did was increased the amount of shock. I had used liquid chlorine - the one you get in Costco since my local pool store didn't have any. It worked. It increased the Free Chlorine also. Please spend some time to calculate the Chlorine required. If you put less, it will not work. I also believe you may need to shock less frequently since your Free Chlorine will be more. But I am not an expert, just a pool owner.
 
nkundagr said:
I had the same thing happened two years ago. Draining the pool water was not an option for me - too costly. It was also in early August. So what I did was increased the amount of shock. I had used liquid chlorine - the one you get in Costco since my local pool store didn't have any. It worked. It increased the Free Chlorine also. Please spend some time to calculate the Chlorine required. If you put less, it will not work. I also believe you may need to shock less frequently since your Free Chlorine will be more. But I am not an expert, just a pool owner.
Click to expand...

The CYA buffers with and binds the FC. This means that you need to run a higher FC to allow enough of the FC to remain unbound and ready to sanitize the pool. Running a higher FC due to CYA doesn't result in "extra" chlorine that sanitizes the pool, it just means you're actually keeping enough FC available to keep the pool sanitized and safe. Running a higher FC to account for the higher CYA will not mean that you to shock less frequently (here, we don't shock, we SLAM, and only when it is needed to deal with a problem in our pools).
 
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