Make my own 50ppm cya calibration?

demento · Mar 28, 2016

New pool owner here...I ordered my tf100 test kit a couple of weeks ago, but have been having trouble building confidence in my ability to measure cya accurately. I wish I had known about the 50ppm cya standard calibration fluid when I ordered, but I didn't, and alas now including shipping, it's a bit pricey.

I have a suspicion that I will have to increase my cya anyway, so I thought that maybe I could buy a jug of stabilizer and create my own 50ppm standard. Is this possible? If so, how can I do it!

pooldv · Mar 28, 2016

1/10th of an ounce, or 2.83 grams, of CYA in 15 gallons is 50 ppm. Maybe have a look at this page first, I found it to be helpful.

https://www.taylortechnologies.com/ChemistryTopicsCM.ASP?ContentID=36

demento · Mar 29, 2016

pooldv said:
1/10th of an ounce, or 2.38 grams, of CYA in 15 gallons is 50 ppm. Maybe have a look at this page first, I found it to be helpful.

https://www.taylortechnologies.com/ChemistryTopicsCM.ASP?ContentID=36

Thanks for the quick reply! Quick correction in case someone else needs this info. The calculation should be 2.83 grams, not 2.38 grams. You transposed the last two digits.

This also assumes 100% pure CYA. Is the stuff we buy at the pool store typically 100% pure?

pooldv · Mar 29, 2016

Dang it! I fixed my post. Some of it is 99% and most is 100%.

Patrick_B · Mar 30, 2016

This test is one people tend to overthink. I admit, it can be easy to do, but trying to minimize that will be very helpful in the long run.

duraleigh · Mar 30, 2016

1/10th of an ounce, or 2.83 grams, of CYA in 15 gallons is 50 ppm. Maybe have a look at this page first, I found it to be helpful.

So, how do you intend to mix up 15 gallons of water and 1/10 oz CYA?

I can see the 15 gallons but if you miss your .1 oz of CYA by 10%, your test is off by that much. It takes a fairly good, calibrated scale to give you .1 oz that you can tr7uly depend on.

My guess is it would be a lot more reassuring to get the Taylor Standard Solution (about 8.50, I think) but it's up to you to decide which best suits you.

demento · Mar 30, 2016

duraleigh said:
So, how do you intend to mix up 15 gallons of water and 1/10 oz CYA?

I can see the 15 gallons but if you miss your .1 oz of CYA by 10%, your test is off by that much. It takes a fairly good, calibrated scale to give you .1 oz that you can tr7uly depend on.

My guess is it would be a lot more reassuring to get the Taylor Standard Solution (about 8.50, I think) but it's up to you to decide which best suits you.

My strategy was to mix up a 'super solution' of maybe 1L that has a very high CYA level, and dilute from there to achieve 50ppm. I have several scales that can measure down to +/- 2mg for my business, so I am confident I can measure the CYA accurately. I was more annoyed with myself that I didn't know about the solution when I placed my order, so this oversight on my part would mean me having to pay shipping twice and wait around for it to come. For that same money, I can buy some CYA (which I think I need anyway). This will allow me to save money and, more importantly, will allow me to run the test today rather than wait for the mail to show up.