I had always thought hot weather was the leading cause of evaporation. The past several nights we've gotten down into the low 60's and even upper 50's with unseasonably cool daytime temps. I was holding a steady water level for weeks, but I've lost about 2" of water since then.

I assume evaporation loss has no impact on some water tests but does on others, like CYA (same CYA content but less water so it increases?)?

I also assume a 2" loss isn't worth worrying about as far as testing goes, especially since I plan to add it back soon?