moderator comment: post moved from here- confusing test results
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.
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.