Little bit more help.

Hey guys, I'm just staring to use hydro, I've read quite a bit about it etc I just thought I could do with a bit more help on these questions,

1) I have a 47 liter reservoir as I'm adding nutrients to the solution I'm going to need some sort of pump, to stop the nutrients sitting at the bottom. Not really for anything else other then to keep the solution mixed up and not let it sit at the bottom, could you suggest a good enough pump for that size reservoir please.

2) I was going to use pure clay pellets for the medium, would you suggest I use something different?

Thanks guys in advanced!

Well for a pump any pump that you can change the angle of out flow will work. Something like a maxi jet 400 or maxi jet 600. For 47L I wouldn't go higher then that. I use the 1200 in my 50 gallon tank.
As for the media it's realy up to you. Each have a up and a down side. Hydrotons down side is if you spill any you will be finding it everywhere Lol. but great air/water ratio. I use it. Grow cubes/chunks are good but topside dosnt realy dry out so can mold. Depending on the hole size in the buckets you can use grow smaller grow rocks like perlite.

First, I would recommend a 40 - 60 gallon air pump. Anything within that range, you'll be good. Take Warlock's suggestion

Second, it really depends on your set up. If your doing Ebb&Flow, DWC, Waterfarms, or Aeroponics - I would suggest hydroton (aka clay pebbles)
If your doing like a drip system with the drippers going straight into your growing medium, I would suggest coco, or a perlite/vermiculite mixture (50/50) with the top 1/2" of your pot being only vermiculite. If your doing a drain and flood table I'd suggest rockwool cubes.