i have had my hot tub for a couple of months now and i have all the correct chemicals 
And exactly what would those chemical be??
but i think i am putting them in incorrectly my soft tub is a m-spa blue it holds 850 litres of water and i have to use ph plus 
pH plus could be a couple of different chemicals. WHAT chemical, exactly, is it (read the label of ingredients)
because my water in my town and surrounding area can anyone help me by answering these two questions 
Huh?

? Please read what you wrote, and correct.
how much of both do i put in 
Both WHAT? You only listed one chemical