Testing for CYA

I've been reading some posts on CYA, and getting some mixed messages about how high a level to try to run.
I have a problem reading the test. One day it reads 40 another it's 50. I think the levels do not change that quickly so it must be the tester.
Does anyone else have this problem? Does anyone have a recommendation?

Sounds like your level is about 40-50. That's probably accurate enough for you to understand the necessary chlorine levels to maintain.

I've received several good tips here on getting more consistant CYA Test results.

Assuming your already using a liquid test and not a test strip;

Make sure the dot has disappeared completely when you take your reading. This is sometimes easiest to judge holding the tube at waist level outdoors, but out of the direct sunlight.

I try to shake up the solution, let it sit a minute, shake it some more, let it sit (while I do other tests.) If you have any question about the reading, pour it back out of the tube into the bottle, and try again, no need for another water sample or more solution :)

Thanks,
I think the "out of direct sunlight" may be key for my problems. I've probably varied how I've done it, and I know it's been different on cloudy days.
I'll be carefull about where I do it and see if I can get more consistant readings.
I've been trying to get my CYA level up to 50 because I can't keep my FC level up without adding bleach every night. I think that a higher CYA level protects the FC. Is this true?

You might want to check this thread, giving several ways to be consistent. It is a very subjective test.

http://www.poolforum.com/pf2/showthread.php?t=1855

Pat

Good advice from cwstnsko. It gets easier with consistency.

Yes, CYA protects Cl from the Sun....that's it's only purpose. The tradeoff is that the Cl is somewhat less effective with higher CYA levels so you must maintain a higher Cl range to compensate. No big deal, just maintain your Cl levels per the "best guess" chart (3-6ppm with CYA at 50ppm)

You will still experience some Cl loss daily. Most pools seem to lose 1-3ppm.