Should Eagle Ray tests be done before or after backwashing the filter?

[Amir Al-Shammari]

I’m not sure if the timing of testing relative to filter maintenance matters. Would testing before backwashing produce different readings compared to testing after the filter has been cleaned?

 

[Afiq Tan]

If you’re going to backwash anyway, I prefer testing after the backwash and rinse are done, the water level is back to normal, and the pump has run 30–60 minutes so everything mixes evenly. Backwashing and topping off can slightly shift numbers (dilution), and testing too soon or too close to a return can catch a weird pocket that doesn’t represent the whole pool.