I dont know why people post if they have no useful input.
Anyways, I use soil, and a trash can res, it works perfect. Running your pump through the wand would be great if it wasnt so damn loud.
A small submersible pump for a fish tank would be great to keep a good mix. I wouldnt bother with an air stone, if you run a line from your mixing pump to the top of the trash can, so the water falls a few inches, it will give you the same effect.
I Never, Ever use the same res of mixed nutes for more than a week. It always works out so I get 2 feedings per res, then I clean and change it.
Some of the things you should not overlook when changing res.
Your Wand. Clean it, clean it well. It doesnt matter how well you clean your trash can if theres a small build up of water festering in your wand. ( this happened to me, then I bought a $50 garden wand that I can take apart and clean, its great)
When you change your res every week, put your pump in a bucket of fresh water, and run clean water through your pump, hoses, and wands. Every Week!
Also I would Get some Clearex or Hydrogen Peroxide (H202), use it for a good cleaning at least once a month.
Good luck man, and now that I think about it I have to go change My res.
