Daily Chlorine test and CYA

[MHumphrey]

I purchased the TF-100 test kit, which comes with the Taylor basic kit for daily tests of Chlorine and pH. I have a couple questions about these daily tests. First my "CYA" level is always between 70 and 80. I don't have any tabs in, or add conditioner or anything. I chlorinate using liquid (household) chlorine. But because the CYA is a little high, i guess my target chlorine is around 8. The thing is, the basic daily chlorine/pH test only goes up to 5. So...

1) Is it normal for the CYA to be staying around 70?
2) Is there a better test kit for daily tests of chlorine? I mean besides the DPD. I don't want to go through all my drops.

Thanks

 

[pwrstrk]

The bleach doesn't add any CYA and if your not replacing a lot of water from splash out, evaporation things like that your CYA will stay pretty stable.
What you cold do since your FC levels are more than the OTO reads is take a FAS/DPD test and see what the FC level is then do the OTO test with the same sample and note what color it turns.
You should lose about the same FC daily. I don't even test FC daily. I just add what it usually takes. Never had algae. Keep a log of what you add to get to your target FC level from various test results and just use that on the days you don't use the FAS/DPD test.
You should be targeting FC of 9 and never below 5 for CYA of 70 and targeting 10 and never below 6 for CYA of 80. ?

 

[duraleigh]

Repeating powerstrk, just observe that strong yellow shade in your OTO test daily and if that shade varies a lot, test with the FAS/DPD. If the shade stays stable, you're good to go.

 

[MHumphrey]

Thanks for the replies. I've more or less estimated about how much FC is lost per day, and add that amount in every day or every other day. When I do the DPD test (usually twice per week) it is pretty much in the neighborhood of where I expect it to be. I do keep a daily log, but every day i do the OTO test, i'm thinking "Why am I doing this?". I just put down 5+ in my log, but really every day it will be 5+. Maybe that is the value of the OTO test - just to make sure it hasn't gone way down for some reason. I guess my eyes aren't so good because anything over 5 all looks the same to me. Could be 6... could be 11...

Anyway, just seeing how others do it.

Thanks,
-Matt

 

[timerguy]

I use the FAS/DPD test for my daily tests. You ought to until you know exactly what's happening in your pool. I assume while you're not using tabs now, you obviously have been using stabilized chlorine -- a lot of it-- in the past.

 

[jblizzle]

To be clear, the TF-100 comes with the FAS-DPD chlorine test ... NOT ... the pink color matching DPD chlorine test. Just wanted to correct your terminology.

 

[tim5055]

Using the OTO test you can "guesstimate" the level of chlorine from Richard320's chart:

On the OTO (yellow) chlorine test:

Blinding tweety-bird yellow is about 10. School bus yellow is about 12-13. Hunter orange is around 18, up around 25 it starts to look pumpkin orange.

I seldom use my OTO test because the Speed Stir is so darn fun, but I guess I could save some of my FAS-DPD reagents and use the OTO some. To be honest I've slipped into the habit of ony checking FC & pH every other day due to my Stenner continuously adding chlorine and the rest (except CYA) on the weekend. This week that caught up with me because of overcast/rain all week and cooler temperatures my chlorine demand dropped through the floor. My FC jumped to the point that I actually turned off the Stenner for two days to allow the FC to drop back down.

 

[timerguy]

Yup, I had to drop the overnight run and production % too.

 

[singingpond]

I've used dilution with the OTO test occasionally, including once for a few days during a SLAM while waiting for new FAS/DPD reagents. If you are careful measuring (I use a syringe that came with some children's meds) this can give reasonably good results, For example, I was trying to maintain FC around 16, and did a 20-fold dilution in order to then guesstimate OTO colors between .5 and 1 ppm -- that corresponded to a 10 - 20 ppm range in the original sample -- that kept me on track enough so that when new FAS/DPD reagents arrived, the FC measurement was within 1 or 2 ppm of what I had estimated using OTO.

At the chlorine levels you're trying to maintain, I'm not sure if it's worth exploring this approach -- it does take additional time, which is a nuisance for daily use -- maybe better just to develop a good eye for the shade of vivid yellow you're looking for on OTO, as previous posters have recommended.