Orenda TechnologiesPR-10000-QT. Phosphate Remover Concentrate, 1-QT.

How much should I add for 25,000 gal inground pool?

Can I use this in a 350 gallon hot tub?

Do you have to vac the entire pool after puttin this in?

Is this nsf safe? (the half pint size indicates nsf safe - is the quart size also?)