Just had pool replastered with dark grey colorscapes about 5 weeks ago. Startup was performed by pool service company. After first month pool looks great and all readings are within range. Pool guy said CH was at 235. I tested the following week with Taylor test kit purchased at Leslies and CH was at 380, which was confirmed by Leslies.
I am now getting a 480 CH reading with my test kit. Leslies is getting a 300 CH reading (as of last Friday).
Am i doing the CH test incorrectly (Swirling /mix)?
Could i have bought a test kit with defective CH test liquid?
Is there a special technique to performing the CH test?
Could there be something in the fresh colored plaster (calcium additive) that is being released during curing process that could be causing CH reading to increase drastically in such a short period?