CYA Confusion

[smittysgirl]

Help!

We took the cover off our pool a couple of weekends ago and the pool was green but very clear. Normally we would then fill the pool, set up the pump, vacuum the bottom to waste, adjust chemicals & SLAM it. This year, life got in the way for a couple of weeks, so by the time we got back to opening the pool last Saturday, it was a green swamp & the bottom was no longer visible. My husband went ahead with the normal process & added in 1 gal of sodium hydrochloride.

After that, these were the initial readings:
FC=5.5
CC=1.5
TC=7.0
PH=8+
TA=80
CH=120
CYA=30**

** We calculated the CYA, since we were out of the reagent, based on our last reading prior to pool closing being 40 & replacing 1/4 of the water through the closing & opening process.

Before bed, we added another gallon of sodium hydrochloride to SLAM it. We didn't have any PH decreaser to adjust PH.

On Sunday night, the FC was back to 0 & we added another 190 oz of sodium hydrochloride.

On Monday, I went to the pool store with a water sample.

Here were their readings:
CYA = 63
FC=0
TC=.3
PH=8.4
TA=98
CH=131

I was confused why their CYA reading was so high, but went ahead last night & added 3 gal of sodium hydrochloride to SLAM it. We also added 1.5 lb of PH decreaser.

This morning, I got the following readings:
FC=45
PH=8+

Based on the above, I'm thinking the CYA was NOT really 63. Unfortunately, I didn't buy any CYA reagent to check it myself, because I figured it wouldn't change from the store's reading of 63.

Wdyt the CYA is based on the above info? I can't get back to the store again today to buy more reagent, but I want to continue the SLAM.

Thanks,
Cecilia

 

[Casey]

You can not SLAM a pool without knowing the CYA.

 

[kcindc]

Wow, you should really take a step back and stop throwing chemicals into your pool without knowing your CYA. Dumping large amounts of chlorine like you have already done will damage your pool liner and equipment. You have small pool and it doesn't take too much to put you in the danger zone.

Which test kit are you using? Get an accurate reading of all of your chems using on the recommended test kits.

Read up on SLAM (see link in my signature). Let FC get below 10 and make sure you PH is where it needs to be before you add any more chlorine.

 

[smittysgirl]

Thank you for your responses.

I have a Taylor K-2005 test kit & a FAS/DPD & use the "classic" pool calculator. I have been using this site & these tools to maintain our pool with good results for the past 6 years.

My initial full test results were taken using the above, as well as today's chlorine readings. The CYA was the only thing I couldn't test for because I was out of the R-0013. I thought the pool store test would be valid, apparently not. As I stated previously, I was confused by the pool store CYA reading because it was my understanding that the CYA doesn't change except if water is replaced, since we only use the sodium hydrochlorozide. The other mistake I made is that I did not adjust the pool calculator up to the 10% bleach, so I put in more than required for a CYA reading of 63. Whoops!

The FC is now reading 3 & latest PH is still showing 8+, I can't tell exactly because it just goes up to 8.

I guess I'll have to wait until I get back to the pool store tomorrow to continue the SLAM process.

 

[Mr Bruce]

You would be much better off getting refills for your reagents than wasting your time at the pool store. I would trust their CYA test the least of all.

 

[smittysgirl]

Apparently...

I buy the reagents at the pool store & had the R-0013 in hand & put it back

 

[kcindc]

First order of business is to get your ph down to 7.2. Then test your cya then continue the SLAM.

Sent from my SCH-I545 using Tapatalk

 

[smittysgirl]

Back again...

I got some more CYA reagent today, here are my latest test results:

FC 2.5
CC 0
PH 7.3
TA 70
CH 120
CYA 0 * The pool store also got this same result.

As you may recall, a different pool store tested the CYA at 63 on Monday.

So, I guess I first need to add stabilizer to bring the CYA up to 40. Right?

Then continue with the SLAM.

Anything else?

Thanks again!

 

[Mr Bruce]

Anything else?

Stop going to the pool store?

 

[smittysgirl]

Right

I just thought of another question...

Should I raise the CYA to 40 or would a lower number, like 20, be more efficient for SLAMing?