- What nutrients do you use?
I have used Dynagro 7-9-5 with good success. I just followed the directions on the back for the hydro method which is 1/4 to 1/2 teaspoon per gallon of water in DWC using Rapid Rooters. Stick seed in the rooter, put some fert in the water, dip a cup into the water and pour this over the rooter a few times a day to keep it wet. Increase the fert amount over time but never measured ppm so can’t discuss that part. At some point, change from 1/4 tsp. to 1/2 tsp per gallon. see what happens. - What size reservoir do you use?
5 gallon buckets each with their own air pump. - How much nutrients do you feed per growing stage?
Discussed above. - How many times do you do a reservoir change per Week? … Month?
As the plants grow they will use more ferts so change when pH seems to be out of whack or ppm becomes a little too low for comfort, or just change more frequently as the plant grows. - Does the amount of reservoir changes change per grow stage?
Not really. But the manufacturers put out ferts for the veg cycle and different ferts for the flower cycle. Your answer might be more due to the passing of time and size of plant than veg vs. flower cycles. - Should I rely on the manufacturers dosing charts?
This is an issue of huge debate. People for years have been following those dosing charts but many times they will come to an internet forum saying “I’ve been using this chart and my plants look terrible.” So I don’t think the charts are great. They might be just a baseline to use, but different strains are said to react in different ways to nutrients. You can get great growth with hydro, but some experimentation is required for new growers, so you might consider using different seeds at first like sunflowers or similar and see how things go. Research this a little more.