Testing CYA levels?

[Chris Roach]

How do you check the CYA level? is there a test kit available?

Also, With my 4 in 1 test kit I get the following #'s

Free Cl = .4
Total Cl = 2.0
pH = 7.4
TA = 70

I take the same sample to the local pool store and they do a BioGuard ALEX analysis with these results

Free Cl = 0
Total Cl = 1.2
pH = 7.5
TA = 134
Adjusted TA = 113 (Whats that mean?)

Why such a big difference in the Cl and TA results from my home test vs. the ALEX test???

 

[JohnT]

Yes, there is a CYA test that is commonly available.

Pool store tests are notoriously unreliable, but your chlorine level can change in the sample between home and the store. Those chlorine levels are probably within the accuracy range of the tests.

Adjusted TA takes the CYA level into account.

 

[PaulR]

You can supplement your test kit with the CYA test, which you can probably get from Taylor and certainly from tftestkits.net. It looks like you do not have a CH test currently, which is not super critical most of the time but can help you diagnose/avoid pitting (plaster/pebble surface) or scaling (any surface type). Finally I bet your chlorine test is the DPD drop test; the FAS-DPD powder/drop test handles a much wider range (up to 50ppm) at .5 resolution so it's the only one that really lets you control your FC level when you're shocking.
--paulr

 

[frustratedpoolmom]

Chris, your 4-1 test kit - where did you buy it, what brand? Unless it's a small Taylor kit, I'd advise you to go ahead and upgrade to one of the recommended kits.

Unfortunately Pool Store tests can be wildly innaccurate. But sometimes its all people have access to until the kits arrive.

You would like the ease of using the FAS-DPD test - no color matching, it's just counting drops till the solution changes from pink to clear, and its incredibly precise.

 

[Guest]

The ALEX system is notorius for overdosing pools. It is designed to maximize chemical sales and NOT balance the water! Find a different store!
Better yet, get yourself a good test kit. A good test kit is the best investment you can make in your pool. It will save you a lot of time, money, and headaches in the long run!
I am going to guess that your 4 in 1 is a Bioguard test kit and the reason it does not have a CYA test will become apparent as you read my post.

We have a a lot of collective experience with testkits and have narrowed it down to two that really deliver for the money. You can read about them here:
pool-school/pool_test_kit_comparison

Anything else just isn't going to cut it. Remember, we don't have a hidden agenda to sell you things (TF TESTKITS is a different thing from TroubleFreePools but we support them because their testkit is a good value for the money and their customer service is incredible but you can also order the Taylor K-2006 from several sources online or directly from Taylor (or the private label version from Leslies. ) Very rarely will you find this kit for sale in pool stores, usually they sell the less expensive (and much less useful) K-2005 which you do NOT want!

A question on your 4 in 1 kit...does the chlorine test turn yellow or red?
I am curious how you got a FC of .4 since that is not the type of number that either OTO or DPD testing would produce but rather the type of results you would get from and FAS-DPD titration which I am sure you do not have. Your chlorine test uses a color comparator, right?

Adjust alkalinity is just TA that has been adjusted for CYA. I noticed that the store did not give you a CYA reading since Bioguard's stance (and the coperate stance of their parent company, Chemtura, all their other brands such as Aquachem, Guardex, Omni, Pooltime, and Sun to name a few) is that CYA levels up to 200 ppm are not a problem in a residential pool. However, we know better and you just have to ask our members if any of them ever had probems from an ovestabilized pool and dropped hundreds at the pool store trying to fix it!
Based on your TA and adjusted TA I estimate your CYA at about 60 ppm which is the high end of acceptable for a manually chlorinated pool. If you are using trichlor tabs NOW is the time to stop using them before you start having problems with your pool.

 

[Chris Roach]

I am going to guess that your 4 in 1 is a Bioguard test kit.
I used a Guardex 4-1.
A question on your 4 in 1 kit...does the chlorine test turn yellow or red? Yellow
I am curious how you got a FC of .4. The color was somewhere between the .2 & .6 comparator

I noticed that the store did not give you a CYA reading. Stores reading was 69 .Based on your TA and adjusted TA I estimate your CYA at about 60 ppm Good guess

Thanks for all the great info, I'll report reading once I get a new test kit. I did however order the Taylor K-2005 prior to reading this response.
I believe I now have a better understanding on pool chem after reading this forum. Thanks for all your responses.

One last thing, and I'll search the forums later tonight when I get time. Any suggestions for ridding the vinyl liner of slight rust stains? there's a ring around the entire pool, approx 6" below the water line and 6" wide, and also some discoloration in the deep end of which appears to be rust?

Thanks again, you guys and gals are great.

 

[frustratedpoolmom]

The ring around the water line could possibly be copper, if you have routinely used copper-based algaecides. Take a vitamin C tablet to the stain and see if rubbing the stain changes the stain's appearance at all. IF its rust the stain will likely fade/dissapear. IF its copper it may not do anything or it may get darker.

The K-2005 is not what you want. It only has a DPD Chlorine test, you really do need the FAS-DPD chlorine test. IF you can cancel or change the order for the K-2006 you would be much better off. The DPD test is just too limited for what you really need.

Anyway, back to the original post, you have CC. YOu need to shock your pool. Check out the CYA chart for your CYA level, and note your Shock level. Then read How to Shock your Pool in Pool School. Keep shocking until your FC holds overnight (this is why you need the FAS-DPD test) and your CC is .5 or less.