i do every other day
1 oz (30ml) neem
1 gallon piss warm water
add dish soap a drop or two at a time and shake (stop adding when the mixture stays mixed)
spray away - for mites, do every 2-3 days for at LEAST 10 days after you see the last mite
for powdery mildew, every other day for AT LEAST 5 days after you see the last mold
it's not a bad idea to do a spray of hydrogen peroxide after one of these treatments (or anytime as a treat for your plants)
i use 3 ml (1/2 teaspoon) per gallon of the 29% solution to RO water
do this before lights out - no direct hid for.... at LEAST till the leaves have dried