Confusing OTO test results

[Nelsonesteves]

moderator comment: post moved from here- confusing test results

Red when you add the OTO drops, which normally turn the sample yellow, means your FC level is very high, 20+. Having TA or CH turn yellow also indicated that the FC level is very high.

With CYA relatively low, it should only be one or two sunny days until your FC level is down to something more reasonable.

There is no need to add calcium to an above ground pool. The only issue with calcium that might come up in a vinyl liner pool is if the calcium level was too high, which yours isn't.

Getting a better test kit is an excellent idea. A kit like the TF-100 from TFTestKits.net or the Taylor K-2006 would allow you to find out exactly what the FC level really was. A top quality test kit will also more than pay for it's self in the long run through reduced chemical usage and avoided problems.

Measure the chlorine and PH levels again today with the WalMart kit and tell us what you get. And don't add any more chlorine until the OTO test shows a more normal yellow color.

The only real open issue is what your CYA level is. When you did the CYA test you said 3 to 50, do you mean 30 to 50? Can you describe what you saw in the CYA view tube?

I think I may be having a similar issue with my OTO (waiting for my TFT fas/dpd test to come in). When I mix the sample it get a nice bright yellow which to me looks like 2-3 ppm but if I add more chlorine and test within 1-2 hrs it's the same color and not the orange color that you would get from 5ppm.

Could it be my FC is too high and the OTO doesn't pick it out? CYA is approx. 30-50 but basing that on my aquacheck sense I'm waiting on my CYA tester as well.

 

[pooldv]

Which OTO test do you have? Do you have an FAS/DPD test to verify higher levels? The Taylor OTO test is yellow past 10ppm of FC and doesn't turn orange until the upper teens or 20ish. It only reads to 5.

 

[tim5055]

Or, some of the inexpensive OTO kits bleach out at higher levels and the solution lightens as the level goes above its limit.

 

[Nelsonesteves]

It's a poolman 5 way OTO test kit. I'm awaiting tfp kit in the mail to do a fas/dpd test and check cya levels.

I was getting frustrated that I couldn't get to 5ppm based on the color chart but now I'm afraid I've gone too high so I didn't add any bleach since last night and this evening I checked and got the same reading of what appears to be 2-3 ppm....

I can see why the other test kit is necessary to know for sure. I've added about 200 oz of 8% over the last three days as I was thinking I had something eating up the bleach. When I added and tested 2 hr later I kept getting the same reading.

 

[jblizzle]

Welcome to TFP!!!

Sounds like the OTO test you have is not working nearly as well as the Taylor OTO. The kit you have on order should make things a lot easier for you as the guessing will be removed.