OK, I have a question.

I have 3 small preformed ponds. Yes preformed. I'm in the middle of moving
them and reconfiguring them to out of sight/touch of the grandkids.

Anyway... I have a 90, 125 and 250 gal ponds. I have 3 bioforce 250/UV
filters and adequat pumpage (I've got pumps out the wazoo..) Here is my
idea. I have 3 55gal plastic drums. I'm thinking of cutting them in half
and doing a modified "skippy" filter approach. I was wondering if I could
use a layer of lava rock instead of the scotchbright pads.

I have a link to the photo here
http://www.ccems.org/images/veggie_filter.jpg

What do I plant in the top? What do I plant the plants in?

I'm a veggie newbie.