CYA testing

[goz63]

So I have the TF-100 test kit but having some trouble with the CYA test. I think I see the black dot sometimes but not sure. I know my CYa was height, 140 and have done quite a few water changes. Dropping to water level 5 inches then filling...rinse and repeat.
I have a fiberglass pool and can’t drain and refill. Will float my pool out of the ground.
any tips on that black dot test? It seems to be light, background, and visual acuity dependent.
Mark

 

[mknauss]

100 is the limit of the CYA test, so you have to do a diluted test. Mix 50% pool water with 50% tap water. Use this mixed sample as your test water. Multiply the result by 2 for your CYA level.
When you do the CYA test, try this next time.

Once you have your solution ready, back to the sun, etc. Fill the vial to a line, say 80, lower the vial to your waist level and glance for the dot, you see it, add solution to the 70 line, glance, see it, repeat until you no longer see it with a glance. Then use the CYA value one step above the line you read. So if you stopped at 50, use 60 ppm CYA.

The vial is in logarithmic scale. So it is not viable to interpolate between the lines. Just use the whole numbers, such as 50, 40, 30, ....

If you need to do a larger volume water exchange, see Draining - Further Reading

 

[ajw22]

Here are more tips...

CYA Testing - Further Reading

www.troublefreepool.com

 

[AusPhil]

I have learnt to mix the CYA test first and then leave it to sit whilst doing the rest of the tests, i'd actually read that as a tip somewhere on this site
Don't be afraid to pour it back and forth to repeat the test .....

 

[goz63]

I understand better the logarithmic explanation for those lines. I did the diluted test when over 100. Thanks for the extra reading. Question though, what is the benefit of mixing first then letting it sit for a while?

 

[ajw22]

Question though, what is the benefit of mixing first then letting it sit for a while?

At a minimum you want to shake about 30 sec; let stand 2-3 minutes; briefly shake again.

If the water temperature is below 70F degrees let the water warm up inside before you do the CYA test.

The standard instructions to mix for 30 seconds is not enough time when the water is cold. You can either mix longer, or allow the sample to warm up to room temperature. Best solution is to allow the the sample to warm up first and then shake it for 30 seconds.

Taylor Technologies has run the pH, total alkalinity, calcium hardness, free chlorine, and cyanuric acid tests on known standard solutions at approximately 104°F, 75°F, 60°F, and 40°F. Only at 40°F did the CYA standard solution test higher than its actual value (after accounting for test variability). All other tests were unaffected by temperature differences.

The melamine solution that is used in the better tests is at low pH so as to force the maximum precipitation of melamine cyanurate since it is somewhat soluble at pH 7.0 with a solubility of around 20 ppm. There is no question that at colder temperatures it will take longer to precipitate.

 

[goz63]

Thank you! I started reading those articles after I posted. My pool is in the 60’s right now as I don’t heat it during winter.
kn another note as I am getting the pool water exchanged the information here is to keep the CYA at 70-80 for a SWG. Just confirming that you don’t want it 50 or so. The pool people here, the guy that installed it and another separate one, both said 40-50. I’m good with not dropping it more. That is a real pain. I don’t want to start adding my other chemicals until I know I am not going to poor them on my lawn.

 

[duraleigh]

Just a bit of a hi jack....

.Taylor Technologies has run the pH, total alkalinity, calcium hardness, free chlorine, and cyanuric acid tests on known standard solutions at approximately 104°F, 75°F, 60°F, and 40°F. Only at 40°F did the CYA standard solution test higher than its actual value (after accounting for test variability). All other tests were unaffected by temperature differences.

Far too often, many of us at TFP overreact to temp sensitivity and advise folks to warm up samples when water temp is 70 or so. Absolutely not necessary, nor is it a cause for a bogus result. ajw22 makes a great post to remind us that these tests are not as temp sensitive as some might think.

 

[mknauss]

Just confirming that you don’t want it 50 or so.

With a SWCG, we recommend a CYA level of 70-80 ppm.

Only reason to lower it would be if you let your FC fall and get an algal bloom. Then to follow the SLAM Process you are better off with a CYA of 50 ppm or less.

 

[goz63]

Ok 70-80 it is. Also Thank You for the top on filling to a level and doing the glance reading. That has helped a great deal. CYA with that approach is 80 this morning. A am going to drop a bit more then start the other balancing. Y’all have been very helpful.

 

[mknauss]

Be sure to test your CYA at least once a month during swim season. It will degrade some in higher water temperatures and also is effected by splash out, overflow, etc.

 

[goz63]

Ok, got the CYA down to 70. Working on all the other readings. That is coming along easily in comparison. I am done draining the pool and refilling! Now just working not he SWG and getting that up to speed. Thanks for all the suggestions and help!

 

[Dirk]

I just wrote a post in another thread that describes how I dialed in my SWG. I converted the instructions a bit for the guy's tab feeder, so you'll have to convert back, but the principle is the same. Maybe you'll find it helpful, as adjusting an SWG can be a bit of a frustrating yo-yo process otherwise:

#60

 

[goz63]

Thanks, read your post. That makes sense. I have the FC where I want it at 4 with bleach. My pool was jacked due to the previous owner new nothing and the pool service didn't know much more. They thought a chlorine pool with a pH of 6.4 was fine. (no kidding they serviced, gave that number and said good to go!). They had been using a chlorinator with pucks and the insidious increase of CY ended up almost 150. Have been draining to drop but that put well water in the pool with sediment and tannins so then had to adjust CH as I have very soft well water. Then alkalinity and pH was high, so fixed that. Almost done. Now adding the salt to get the SWG up and running. Close.

 

[Dirk]

Be sure to let the salt mix in for at least 24 hours before you fire up the SWG. Be patient. I let mine mix in for quite a bit longer, just to be safe. You don't want patches of fresh water and then salt water and then saltier water flowing through an active SWG.

You can shorten the tuning process if you use consistent FC testing methods, especially testing at the same time each day. FC can move around a lot during a 24 hr span. Similar daytime temps from day to day is ideal. Just nit-picking. It's not all that hard to do, and as I mentioned, the SWG setting has to change throughout the year to accommodate temp and bather load swings, so you'll get lots of opportunity to figure out your own MO.

I'd sympathize with your tale of previous owners and inept pool guys, except most of the members here have the same or similar stories! Mine are doozies!! It's why TFP exists. The good folks here created the site, and the TFP methods, to rescue the vast majority of pool owners who fall victim to the incredible amount of mis-information floating around, especially that which comes from "pool professionals." You're in good hands now...