Opening Pool for Summer - Issues testing for CYA, etc

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W

whiskaz

0
Jun 21, 2011
25
Parkersburg, WV
I cannot, for the life of me, get an accurate test for CYA. 10k gallons, vinyl, above-ground. Last year when I bought my kit, the CYA test did not register after multiple tries. I added CYA (I forget exactly how much, enough to get it to 40, via sock).Tested sometime later, no reading. So I went ahead and added the same amount again, via sock. I eventually got my pool cleared up and basically just maintained my FC between 4-8 even though I had no real clue what my CYA was at.

Fast forward to now. I'm starting to open the pool for the summer. It was green. I still cannot get an accurate reading for CYA. I can tell you that I somewhat haphazardly added 12.5% to the pool for the passed week. I was basically trying to keep the FC "high" (around 20). There were times when I would have it so high that I stopped adding drops of 871. I would test later or the next morning only to have the FC around 6ppm or less. CC has been anywhere from .5 up to 3.

My most recent test, this AM had the FC very high (again, I haphazardly added 4 gallons last night, because the FC seeemd to be going pretty quick). This AM my tests were as follows:

FC: 33, CC: 3, PH: 8, TA: 90

The PH is high this AM, but I've been keeping it down around 7-7.2 with muratic acid. It will drop for a day or so only to come back up. I added some more muratic acid this morning but nothing else. I will re-test everything again around lunch time if I can get home.

I wish I had a better idea of what my CYA level actually was. I can't believe that it's actually ZERO since I added some much stabilizer last season.

I also seem to have some SAND in the pool. I'm guessing it's play sand from the kids but I'm not sure. I can't seem to get it off the walls with a standard brush. I pulled the stairs out of the water and there's quite a bit of sand on them.

I've backwashed the filter (but need to get a new guage because the current one isn't reading at all). The glass jar looks clear. I may replace the sand in the filter anyway, as it's been several years or more. I haven't officially swept the pool but I've brushed it daily and gotten most of the dead leaves out I believe. I will sweep it this evening if possible.

Sorry for the long windedness. The next one will be a lot shorter, with just test results. I promise!
 
Actual sand would brush right off. Sand like roughness that doesn't brush off is usually calcium scaling.

There is almost never any reason to replace the sand in a sand filter. About the only time it needs to be replaced is when it has become scaled.

CYA often disappears over the winter. There have also been occasional batches of stabilizer/CYA sold that don't actually contain any CYA.

One way to judge your CYA level is to measure how much chlorine you lose over the course of a single sunny day and compare that to how much chlorine you lose overnight. If you are losing chlorine overnight something else is wrong. If CYA is zero you will lose all of your chlorine during the day. With CYA around 40 you lose about 50% of your chlorine (if the pool get lots of sun). It's only a rough estimate, but a good way to double check you test kit.

If your CYA level is anywhere near zero, you are adding way too much chlorine.
 
I will re-do my test for CH (because I didn't think it was that important for a vinyl pool). The one test I did registered very low, like under 50. I will also do a little more research on scaling. It certainly isn't coming off easily!!! If I rub my hand on the wall hard enough I can get it to go. The only reason I assumed sand was because there's sand on my plastic stairs (which I removed from the pool yesterday). It comes right off though.

I am losing chlorine overnight and during the day, I just haven't been good about recording results. It didn't seem to matter how much I added, it would all be gone after a period of time, both during the day and overnight. Anyway, I'll start tracking better now.

I may purchase some more CYA and add just a tiny bit to see if it starts to register. I suppose I could have gotten a bad batch last year.

Thank you!
 
Losing chlorine very rapidly when opening in the spring, combined with all CYA disappearing, is a known thing. Certain kinds of bacteria can break down CYA over the winter, turning it into ammonia. It can sometimes take a great deal of chlorine to get rid of the ammonia (chlorine and ammonia combine very rapidly to form CC, which is subsequently broken down by using more chlorine).
 
duraleigh said:
I still cannot get an accurate reading for CYA.
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You say this in your first post but you don't say why. Could you share the issues you are having with the test?
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I just assumed it wasn't working (last summer) because I added around 4lbs of stabilizer and never got the dot to disappear doing the CYA test. It's possible, according to Jason, that I just had a bad batch of stabilizer. I'm afraid to add more though in case I'm just not testing right (I've read up on it and I believe I am).

...

Previous test 7AM. As of noon today (sun is out in full force):

FC: 22 (-11)
CC: .5 (-2.5)
PH: 7.4 (-.6)
TA: 90 (0)

No change in the look of the water.
 
duraleigh said:
Sorry to be so thick-headed but I still do not understand if you have performed a CYA test this season. If you have, what was your result?
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Sorry, I wasn't very clear either. I have performed the test twice in the last week and received the same result- 0. I just didn't have faith in that because of my results last year (0, even after adding a bucket of stabilizer). I actually added the stabilizer in 2 parts last year, not all at once, and waited before testing each time.
 
and waited before testing each time.
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Perhaps you didn't wait long enough last year....you should wait one week.

If the solution is clear this year (You can see the dot even after the view tube is completely full), you can be assured you have zero CYA and will consume excessive amounts of chlorine (and get algae) until you get CYA in your pool.
 
So yesterday evening I was down from about 22ppm of FC to 1ppm. I added approx. 30ppm of stabilizer (I got a bottle from the pool store, argh, and it was only good for 20ppm so I used some from the batch I had last year to get to 30- a different unopened bucket, so hopefully it was OK). I'm assuming 30ppm of CYA now until I can test. I may add more to get it up to 40.

Around 7 I added enough chlorine to get me to shock level. Measured the FC about an hour later- it was at 18ppm. This morning I was at 15ppm so I didn't pass the OCLT. CC was around 1. Since 15 is shock level for the amount of CYA I believe I have, I did not add more chlorine this morning.
 

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Well, I realize I didn't wait a week to test the CYA but the test is definitely showing some CYA now. I've only lost .5ppm of FC since 6AM this morning which is much better than normal.

pH is a little low now, tA looks good. Pool still looks horrible. Very low/almost no visibility. Patience I suppose...
 
Patience I suppose...
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Well, yes, patience and continue all the things you do in the shock process. Replenish your FC right back to 15ppm every chance you get, brush the floor and sides when you can, vacuum when you can, and watch your filter psi. As it catches the stuff that is making your water cloudy, your psi will rise. When it gets 25% above normal, backwash/clean and start again.
 
Follow-up. After blindly getting all of the leaves, etc off the bottom and passing the OCLT and having 0-.5 CC, the pool was still wicked cloudy. I was backwashing daily, things look clean via the sight glass. The filter pressure doesn't seem to rise above 15 (or maybe I just wasn't giving it enough time to get dirty enough).

Long story short. I cheated. Used floc. Shut the pump off for a day or so (kept an eye on chlorine levels). It rained quite a bit which kept me from getting out to sweep it right away. Wow. Pretty nasty layer of stuff settled to the bottom. I got much of it swept to waste before my water level got too low (I have a crack at the end of my hose and when the water gets below it, it starts sucking air... need to fix that). The bottom is visible but there was still junk left that's now swirled up again so it's not crystal clear. I won't have time to sweep to waste until after the weekend so I will just let the filter do its thing (hopefully it's working OK and doing something!) and keep an eye on the chlorine levels.

CYA is now around 45 too. pH and aK look good. This is the earliest I've had the pool swimmable (despite being a little cloudy, levels are in check). I used to fight with it until mid-June or July. Then I found TFP :) Thank you!
 
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