Hi Darren, i just looked for the dilution ratio online.
LIQUID FORMULA 90
Add 1L to 20L of water in your TM stock solution. That's 50ml per litre, 25 litres = 1250ml (1.25 litres). Set flow metre to 2gph for light soil, 4gph for medium soil and 6gph for heavy soil.
POWDERED FORMULA 90
T/M stock solution 24 scoops to 20L water. That's 1.2 scoops per litre, 25 litres = 30 scoops.