Continue writing the next sentence.

How to mix hydroponics nutrients
Know what's in your water.
Send your water to a lab to be tested, if you can. With good, " soft " water, you'll be able to add any nutrients your plants need for their optimal growing season.
With " hard " water, you may need to use reverse osmosis methods to filter out any unwanted heavy metals present in your water. You can also use a dissolved solids meter to check your water regularly.