Phosphate kit accuracy?

[waterbear]

Well, It seems you have found that your 'limiting factor' IS phosphates.
I've looked over the NaturalChemisty test kit myself and it seemed OK for the price. Chemisty behind it is sound! Basically the same as most of the aquarium phosphate test kits. There are liquid kits available but they are pricey! I wouldn't worry about the accuracy. You basically want to get as close to 0 ppb phosphates as you can! (no blue color) Bottom line seems to be phosphates in your fill water so their products (or other lanthenum chloride based products) should work for you! You will probably need to to the full treament (yes, it IS a major pain in the butt, but it actally works!) to get as close to 0 ppb as possible and then add a maintenance dose every week or two, espececially after adding water to your pool. Good luck!