My CYA is still 100 after draining almots 40% of my water

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H

hrizley

0
Apr 20, 2015
19
Oro Valley, AZ
Hello there!

So glad to be a member of this amazing forum!
Our pool is less than a year old. It is a chlorine pool that holds 17,000 gallons. We have had a very easy time maintaining the chemistry of the water these past 10 months. Unfortunately, I accidentally forgot to add chlorine a couple weeks ago and the pool sat at zero FC for about a week. Algae grew -- no! It wasn't a bad case obviously, but in my haste to fix the problem, I added two packets of Aqua chem shock (which contains dichlor -- I realize this is a huge no no now!) Our CYA levels went from about 40 to 100 with the addition of those two packets of shock. I took my pool water to Leslie's to have them test it and verify it. They too couldn't believe that the packets of shock raised it so high, but it was true. We immediately rented a sump pump and drained out about 7,000 gallons of water from the pool and refilled it this weekend. The only thing I have added is muriatic acid to lower the PH down to 7.5 so I could SLAM it. We added bleach this weekend and the algae is gone. I tested the levels today and was SHOCKED to see that our CYA is still at 100! How is that even possible? Am I missing something? Help! :eek:( I feel like I just wasted a lot of time and energy for no results.

Thank you in advance.
 
I have a few questions, then a comment.

*What test kit are you using?
*When did you test the CYA and get 40?
*What do you use on a daily basis to chlorinate your pool

Now the comment,100 is the limit of the CYA test, so you have to do a diluted test. While the full instructions are in the Pool School, here is the short version. Mix 50% pool water with 50% tap water. Use this mixed sample as your test water. If still at a 100 you will need to dilute more. Here is a great chart by JamesW to explain dilution rates and what you multiply the results by to get an approximation of your CYA level.

Pool water......Tap or distilled water.........Multiply result by

....1...................1................................2
....1...................2................................3
....1...................4................................5

Do a diluted test so we can see where your CYA really is.
 
:wave: Welcome neighbor!!! I am just down the street :D

Step 1: Stop going to Leslies!!! I can not emphasize this enough.
Step 2: Invest in one of the Recommended Test Kits and take control of your pool.
Step 3: While waiting for said test kit, keep reading the forum and take a look through Pool School have you read? Start with these:
ABCs of Water Chemistry
Recommended Pool Chemicals
How to Chlorinate Your Pool

The fact that they could not explain the CYA rise just proves they do not know how to test properly. Using PoolMath, with a 17k gallon pool + 2 pounds of dichlor ... you would have only added 7 ppm of CYA. That is chemistry. So either your pool is WAY smaller, or the bags you used were GIANT, or there test is wrong .... those are the only options :D
 
Thank you for the replies! I added all my pool information to my signature -- sorry I missed doing that before!

The test I have been using for all my pool chemical results is the AquaChek test strips. I see now that I need to order a better kit, which I will do. Pool School has been so helpful and informative! I was hoping my test was wrong, that is why I took it to Leslie's to have them try testing it too. The morning I added the shock (2 1 lb bags of Aqua Chem which contains 58.2% dichlor), I tested my water right before. The levels read:

FC: 0
PH ?
TA: ?
CYA: 40

I have never added an CYA to the pool since start up, and have only shocked one time last June. Our CYA has always been in the 40ish range. When I tested after adding the AquaChem, I was devastated by these results:

FC 4
CH 250
CYA 100
TA 120
PH 7.6

I just don't understand what happened. I have tested the CYA dozens of times and it was always in the 30-50 range on my test strip. The spike from the dichlor is what I am still most shocked about.

I did the diluted test and came back with a different result -- thank you for the suggestion! The test strip was kicking my range up to 100 as there isn't any color for anything between 51-99 on my test strip.
Here are my updated readings from today:

FC 16 (still coming down from SLAMing)
CH 150
CYA 70
TA 90
PH 7.4

This is after draining out about 7,000 gallons over the weekend. Does that seem right? I swear I thought the CYA would have gone down a little more. I'm just glad for the new test because at least it's not still 100!
I guess I remain confused about the initial spike. I will never use anything aside from regular bleach ever again. Do you think that my CYA level will gradually fall over time back down to normal range? Do I need to add any calcium?

Thanks again for all your help! I feel like my pool is a mystery right now!
 
The test strips are messing you up. They sure are easy but they are not accurate at all.

Please just add chlorine to your pool until you get your test kit. Doing anything else right now may do more harm than good :(

Let us know when your test kit comes in and we can help you with your levels.

Kim
 
I would have to say that chances are good that your "100" cya was higher than you thought or your drain was much less than 7000 gallons. Assuming your numbers were correct, your new cya should be about 60 at this point.

What is the actual layout, size and depth of your pool? Knowing that info, you can calculate how many inches to drain / raise to get a required number of gallons.
 
To be blunt you really don't know where you are. The two methods of testing your water you have used (test strips & pool store) are both terribly unreliable. You may have had high CYA for a long time and never really knew it.

At this point I would get a test kit on order and keep chlorine in the pool to keep it from going green.
 
tim5055 said:
To be blunt you really don't know where you are. The two methods of testing your water you have used (test strips & pool store) are both terribly unreliable. You may have had high CYA for a long time and never really knew it.

At this point I would get a test kit on order and keep chlorine in the pool to keep it from going green.
Click to expand...

+1

Not much to add to that.
 

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Hello again! My Taylor K 2006 came today. Hooray! I am SHOCKED at how incorrect the pool store and the test strips are. I am actually mad about the store. They are so off!

Anyway, here are my new results.

CYA: 90
FC: 14
PH: 8.0
TA: 20
CH: 180

The dimensions of my pool are 6 foot deep end, with a 3.5 foot shallow end. 98 linear foot rectangle, with a pop out for an 18 inch oasis. We drained a little over a foot and a half and estimated that it was about 40% of the pool water.

I feel so sad and frustrated. I know that over time I can repair my pool chemistry. What should I do at this point? I don't want to mess up anything any further. I hope to be an expert soon!

Thank you again!

- - - Updated - - -

Doesn't that seem like a really really low TA?
 
Well, your FC is actually still a little high for your CYA, pH is high and yes, TA & CH are low. I don't think I've ever seen anyone from AZ with low CH:confused:

Lets add some baking soda to get the TA up around 50 at least. Let that circulate 30 - 60 minutes and retest. At that point muratic acid to bring down the pH. The MA is also going to bring down the TA a little, so keep an eye on that and adjust as necessary.

The bigger question is, what are you going to do about the CYA. You will need about a 33% water exchange to get it to a more manageable 60. How much rain in your area. If it is higher than average you can live with the CYA and bring it down over time. Or, a third option is to check out the new CYA reducer being discussed on a couple of threads. That is still in the "experimental" stage, so we are not fully endorsing it yet. Lower CYA will keep your chlorine costs down for your SLAM.
 
Okay, I just tested the TA two more times because that didn't seem right. Don't know what I did wrong but it is 150.

- - - Updated - - -

Hello there Tim!
Thanks for the reply. I think my CH is low because we just emptied out so much water? Do you think over time that will rise, or do I need to add something?
Sorry about my initial incorrect TA reading.

I don't think that my husband is going to go for another day of draining the pool, since we just did that on Saturday. Obviously we didn't drain enough; I should have gotten the correct test kit first because obviously my CYA has been higher than I thought for quite some time.

- - - Updated - - -

Is my PH so high because of all the chlorine we added to kill the algae? I looked at the chlorine chart and it says that I should keep my chlorine at a 10 with my CYA range. Wow! I assume then that it is safe for swimming once we get it down to a 10? Darn, I hate having my CYA so high!
 
I don't think we will drain the pool again. We don't get a lot of rainfall in Tucson. We will get a few inches in July when the monsoons come. Not sure how long it will take to lower the CYA, but I don't plan to use tablets ever again. I will chlorinate as needed with bleach. Should I just leave my chemicals as they are? Do I need to raise my calcium?
 
First get the pH down a little, 7.5 - 7.8, then yes the CH should be 250 - 350 for your plaster pool.

The elephant in the room is the algae you reported. You should read the directions on SLAMing your pool in the How To section of Pool School and follow that procedure completely to the end.



  • CC is 0.5 or lower;
  • You pass an OCLT (ie overnight FC loss test shows a loss of 1.0 ppm or less);
  • And the water is clear.

When all three are true, you are done SLAMing and can allow the FC to drift down to normal levels.

With 90 CYA you can never let your FC get below 7 and target 10 - 11 in your sunny location. The killer is that with your CYA shock level is 35. You would need to bring it to that and hold it there until you pass all three tests in the SLAM.
 
hrizley said:
Thanks for the reply. I think my CH is low because we just emptied out so much water? Do you think over time that will rise, or do I need to add something?
Sorry about my initial incorrect TA reading.

Is my PH so high because of all the chlorine we added to kill the algae? I looked at the chlorine chart and it says that I should keep my chlorine at a 10 with my CYA range. Wow! I assume then that it is safe for swimming once we get it down to a 10? Darn, I hate having my CYA so high!
Click to expand...
I just noticed I missed these questions

CH rise will depend on the CH level of your fill water. As pool water evaporates it leaves the CH (as well as CYA and other stuff) behind. You fill the pool up with the hose and add more CH and the cycle goes on and on. You can test your fill water (right out of the hose) to see if your fill water has a high CH to get an idea of how fast it will rise.

Any aeration will cause pH to slowly rise. This includes SWG, fountain, spa, waterfall, other water feature or even the return jets of the pool pointing up and breaking the surface. Once you get it nice, you swimming around raises pH. I add acid to mine a couple of times a week to bring it down.
 
With splash out and rainfall (we don't get much in Tucson!...maybe a few inches this summer), how long would it take for my CYA levels to fall naturally?

Also, will that much chlorine be really irritating to the eyes and skin? Or does it get "cancelled" out due to the CYA? If we have to keep our pool at 7-10 FC, that might be reason enough to drain it again.

I know that there is that new product to reduce CYA. I've been reading about it on here and it seems like it's a mixed bag.
 

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