How much feed should you introduce into a swim when fishing. How much what and when. At what sort of intervals should it be introduced.
When I am fishing for Barbel I will first cast out maybe half a dozen, to a dozen cages of feed to the same spot. I will use a medium sized cage feeder containing a mixture of swim stims, standard groundbait for barbel, and most importantly lots of hemp!
Once you have fed your first lot of groundbait, keep the cage on your line and use it as your ledger. On each cast, bait up using luncheon meat/boilie/pellet etc and cast out with a full cage of groundbait. Then wait! Different people will tell you different things, but I will generally wait around 20-30 mins or longer before reeling in and rebaiting. Then refill up your cage feeder and recast to the same spot you baited up.
Hope that helps! If you have any questions or want more detail just post an answer after this.