CYA testing - before start up?

[waterbug]

Hi folks - it's getting close to opening up time again - looking forward to that!
Quick question - is it okay to test CYA before opening - before starting up the pump actually. I am thinking I may need to dump half the pool and would like to be able to do that and refill before starting the pump and working on other chemical levels. Planning to go BBB all the way this year.

If it is not alright, I would need to fill up and run the pump for a bit and then test and maybe dump out the new water.
Thanks, waterbug.

 

[duraleigh]

If running the pump for 20 minutes first is a hassle, I'd say take the test first. CYA should be distributed evenly but, "should" doesn't always work out. Any test is more accurate if you can distribute the water in your pool for a bit.

 

[JasonLion]

The CYA level isn't always uniform if the pump hasn't been running. Also the CYA level can read higher than it actually is if the water isn't very clear, which it often isn't first thing in the spring.

 

[Guest]

If you KNOW that the CYA was too high when you closed one of two things have happened--you still have high CYA or anerobic bacteria have degraded the CYA to ammonia compounds. Either way a water change will dilute the 'offending' component in your water and make your startup a bit easier. In the case that everything was OK when you clsoed it means you are out the water you changed and whatever CYA you need to add to bring it back up to the correct level after the water change. Filling the pool and circulating it and THEN testing the CYA is the only way to really know how you stand now.