Liquid NPK + M This product is tailored to the EI dosing method but can be adapted to other dosing techniques Dosing for full EI levels is 1 pump of each bottle per 10 gallons 3x per week For lower light/lower tech tanks dosing at 1 pump per 20 gallons 3x per week For example: For a 20 gallon higher light tank would be as follows- 2 pumps of the micros per day Monday, Wednesday and Friday 2 pumps of the macros per day Tuesday, Thursday and Saturday 50% week water change is suggested on the 7th day per EI guidelines followed by addition of the GH booster of your choice(I have some for sale below in the dry ferts section) Bottles are 16oz each This will last more than 41 weeks on a 20 gallon tank dosing 3x per week. Who needs GH booster: Unless you have very hard water it is very likely that the addition of Gh booster is necessary. Even if you do have hard water unless you know the concentration of both calcium and magnesium adding some GH booster is suggested. Why is GH booster suggested: GH booster will add magnesium and calcium as well as add extra potassium which are all very important to plant growth.