Subscribed to the Newsletter and the Youtube channel.
As far as current testing goes:
Salinity - Cheap refractometer
Temp - 2 different cheap aquarium thermometers, try to average between the two.
I haven't been monitoring phosphate levels, although I really need to...
Bonus I test with a Hanna phosphate checker, but have been wanting the ULR Checker for some time. I check Salinity with a refractometer and would love to switch to digital