CYA very high; run other tests anyway if have to replace water? Newbie

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contrite&reformed

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Aug 10, 2014
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Central Ohio
Newbie here.

My Taylor K-2006 arrives today. I have pool store test numbers now.

Pool is yellow-green and cloudy with yellow powdery stuff on bottom. I won't go into how it got this way, but it's been like this for more than a week. Thank goodness for this website, which I found over the weekend.

In an effort to kill the algae, pool was shocked several times with powdery-shock stuff, then Clorox. Totally unaware of the contrution this and the chlorine tablets we were using made to the CYA levels, we've been using them for some time. They've been returned to Costco. Just prior to finding your website, I read something online about the Taylor test kit and ordered it; we've been using strips which have been less than helpful. Pool pump has been running constantly for a few days. Backwashing filter reults in no appreciable difference in the look of the sight glass. Planning to add DE (Sparkle?) to pump, since sand is apparently not catching the fines going through.

The pool store attendant tried to test the water yesterday and said it couldn't be tested because the chlorine level was too high. I suggested he dilute it by half with distilled water and run it, which he did.

the following are numbers from the 1:1 diluted test:

CYA 56
Total Chlorine 10.9
Free Chlorine 10.3
pH 8.2
Tot. alkalinity 63
Adj. Total Alkalinity 46
Tot. hardness 45
Copper .1
Copper from Products Yes

He ran the numbers telling the machine there was no algae, black, green, or mustard.

The high pH prompted me to add muriatic acid to the water in the amount suggested by the PoolMath Calculator, so I'm reasonably certain it is probably now more in the 7.5-7.6 range. I haven't attempted to deal with anything else.

MY MAIN QUESTION: Once the test kit arrives, is there any point to running tests other than the CYA test, since from what I've read here, if the high CYA level is confirmed, I'll need to replace a significant amount of the water?

Second question: Would it be correct to brush and backwash the pool before draining? Rinse walls with hose as it drains?

Third question(s): Since there appears to be an algae issue, should we drain the whole thing instead of the 73% (or whatever) the PoolMath calculator suggests? How full does the tanker need to fiil it to have it out of danger from the surrounding groundwater? Just below the skimmer?

Thank you all for all of the advice on this site!!
 
:wave: Welcome to TFP!!!

1) Would not hurt to test everything, but the CYA is the driver to know if you need to replace water.
2) Seems like a good idea as it would remove some of the algae. How are you going to drain? You should not do it on backwash mode.
3) You can not drain it all unless you plan to buy a new liner. You must leave at least 1 foot of water in the shallow end to avoid the liner shifting/shrinking. Ideally you want the pool water level above the ground water level at all times.

Forget about adding DE to your filter now. You need to get all the algae dead first and then use DE at the very end to help with the cloudiness (if required).

BTW, start shopping for refills for the CYA and FAS-DPD reagents as the K-2006 does not come with enough and you will likely run out since you need to follow the ShockLevelAndMAINTAIN Process.
 
Thank you both for the quick reply!

We have a pump to remove the water.

If I leave a foot in the shallow end, I don't think I would be removing anything near the amount needed to get to a reasonable CYA level. Can't afford to replace the liner.

If there is a foot in the shallow end, can I fill with hose, or do I need a wuick fill from tanker?

Already bought refill for CYA testing.

Thanks again!
 
I was under the impression that I don't have an option to leisurely fill the pool with a hose with a vinyl pool--is this incorrect?

We don't use our well for anything. Lots of iron. No metals that I know of in our municipal water.

Here are the hot-off-the-press Taylor test numbers:

CYA over 100, but not a lot over
pH 7.4 (thank you, PoolMath Calculator!)
Chlorine 31.0
Total Alkalinity 140
Calcium hardness: ~110

I'm going to try again to attach photos. Last try, it said I didn't have permission or access or something.

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How did you go from draining the entire pool to only draining to below the skimmer (like 3")?

As I said in the first reply, brushing and vacuuming to waste is a good idea. Although until you get up to shock FC level for your CYA, the algae is going to continue to reproduce, so your brushing and vacuuming may be wasted effort.
 
Draining the whole pool is apparently not an option. If I'm not needing a tanker, it seemed okay to do this more gradually. I thought I'd recheck the CYA after refilling the first 4" we vacuumed to waste, then SLAM it, vacuum to waste and brush it until it's back down to the bottom of the skimmer and repeat.

Not such a good idea?
 

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It is going to take a LOT more water that way. Did you ever confirm the CYA level with the diluted test?

Lets say your average pool depth is 56" ... if you replace 4" that is only 7% ... so your CYA will go down by 7%. If it starts at 120ppm then after replacing 4", it will be 112ppm. You would have to do this 12 times to get down to a CYA of 50ppm. So a total of 48" of water would have to be replaced.

If you could do it all at once, you would need to replace 58% of the water or 32.5" of water (33% less water drained than above) which might be too much if that will not leave a foot of water in the shallow end.

So you likely could do it safely with 2 larger water replacements of 20" each.
 
It will take more drain/refill cycles and a larger total volume of water to lower your CYA if you only do the draining down below the skimmer and refill and repeat. As long as you don't have a high water table in your area you can safely drain a vinyl lined pool so you have a foot or slightly less in the shallow end. This prevents the liner from shifting or wrinkling. You're best served draining as much as possible before refilling, in a safe manner for your liner. It's looking like to get into the 50 ppm CYA range, you need a 50% water replacement. Taking it down to a safe level for your liner, well below the skimmers is your best bet. Then refill and start adding bleach to keep algae at bay until full. A couple gallons during refill is enough to keep things in check.

Use Pool Math to help determine how much water you need to replace. Verifying the CYA with your K-2006 kit. It's more accurate than the pool store. Repeat once you've refilled and tested CYA again.
 
We have probably been adding a couple inches of water a week to the pool over the past several weeks, because of evaporation and a probable leak. Leak source is not yet discovered, but we'll deal with it (thanks to good info on this site regarding how to attack it) once the algae issue is under control.

Our thought at the moment is to bring the CYA level down--even to 75 or 80--and SLAM the pool, get rid of the algae, then continue to replace the water over time. As the algae is zapped, it will be vacuumed to waste and we'll have to replace that water. We'll never use chlorine tablets or shock again, so the CYA level is not going to go up.

One question now is what chlorine level is acceptable for swimming? Since we'll have to have the chlorine level continuosly high to SLAM the pool, will it be unswimmable once the algae is gone?

And how do I know whether I have green algae or yellow? It looks much more yellow to me than the very green algae we've seen and zapped when opening the pool late in the spring. Should I just shock at the green level and see what happens?

I appreciate very much all of the advice being shared here!
 
If your CYA is really that high, your shock level will be roughly 47-50ppm, possibly higher depending on which algae you have. That is going to take a lot of chlorine for the SLAM process.

When CYA is that high, the possibility of algae bloom is increased because high CYA neutralizes the chlorine.

Better off draining and refilling to bring down your CYA.
 
contrite&reformed said:
We have probably been adding a couple inches of water a week to the pool over the past several weeks, because of evaporation and a probable leak. Leak source is not yet discovered, but we'll deal with it (thanks to good info on this site regarding how to attack it) once the algae issue is under control.

Our thought at the moment is to bring the CYA level down--even to 75 or 80--and SLAM the pool, get rid of the algae, then continue to replace the water over time. As the algae is zapped, it will be vacuumed to waste and we'll have to replace that water. We'll never use chlorine tablets or shock again, so the CYA level is not going to go up.

One question now is what chlorine level is acceptable for swimming? Since we'll have to have the chlorine level continuosly high to SLAM the pool, will it be unswimmable once the algae is gone?

And how do I know whether I have green algae or yellow? It looks much more yellow to me than the very green algae we've seen and zapped when opening the pool late in the spring. Should I just shock at the green level and see what happens?

I appreciate very much all of the advice being shared here!
Click to expand...

It's OK to use chlorine tablets when needed such as vacations, just as long as you understand how they affect your pool chemistry and long term maintenance.

I would try to lower to at least 50 or so. It makes a big difference on how much bleach you'll need to start and complete the SLAM process.

Once you're done with the SLAM you use the Chlorine/CYA Chart to determine your maintenance levels of FC. This chart also tells you the level at which you need to maintain during a SLAM. Any FC level at or below the SLAM FC level indicated is safe for swimming. Also, once you complete the SLAM your chlorine level will gradually fall to the maintenance levels due to sunlight and bather load, then once it hits the lower end (minimum) of your indicated FC range, you dose daily with bleach to bring it back up to the Target level. Once you get to that point, it's actually very easy.

I would SLAM at the normal Shock FC level listed on that chart and go from there. Mustard/yellow algae can be a different animal but just approach it like it regular, run-of-the-mill algae for now. Get yourself familiar with TFPC methods in the Pool School link, starting with this article is a good bet ABCs of Pool Water Chemistry
 
I had to lower my cya last year from 350 to 50. It took 5 --1/3 drains and refills each one leaving ~ 1 ft in the shallow end to protect my vinyl liner. That's the least amount of water I was going to use to rectify my situation. I did one/day, so it took me 5 days. Refilling the pool took substantially longer than draining it.
 
Thank you all again so much! I'm looking forward to being algae-free with a low CYA.

I hadn't thought about tablets for vacation. But then, we haven't taken a vacation for a long while, either.

I can't imagine what kind of chlorine level was needed for a CYA of 350!!
 
I didn't know about cya for the first year I had my pool I couldn't figure out why I had recurrent algae problems. Then I found tfp. At first I didn't believe my cya was high because for months leslies had been telling me it was 40. I also refused to believe it was a problem because my water was sparkling blue except for when I was having a bloom. I finally came to my senses and became a believer. Got my cya to a decent level and haven't had a problem since. Well, except that my pump stopped pumping saturday so I've been pouring in a bottle of bleach every day until I get my new pump delivered Tuesday.
 
The pool is looking much better--it's such a good feeling to actually know what's going on with it! Very reassuring. We're vacuuming a bunch of stuff to discharge now, then will do another water reduction, check the water, add stuff, and wait til morning.

Our pool has also always been sparkling blue until now. I suspect that between water leaks in the liner a couple of times, liner replacement, and liner shift requiring draining, we've been replacing the water over the years from time to time, and thus lowering the CYA without knowing whether there be such a thing as CYA. As soon as I read the posts on this site, I was a believer.

More chemicals to test chlorine arriving tomorrow. i had ordered replacements for the CYA test when I ordered the test kit. Good thing--the little bottle in the kit had to be refilled already.
 
Have you done the diluted test Jason suggested to get a more accurate cya level than not much over 100? I couldn't see the black dot unless I emptied the test vial. so eventually, I too found my cya to be not much over 100 as in about 250 over 100 :)
 

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