Saved tadpoles & homes/pond I built for 'em (picture heavy)

JHK30

awe thats cute. I also grew up tadpoles. I took a garbage bag and buried it in my sand box and then they disappeared. before I could say bye to them =( stupid legs! they just had to grow.

But this summer I am putting a 20 gallon long out into my sand box but i am not burying it and I am getting some feeder fish and tadpoles to put into it. and I will get some of my irrigation pond plants and put them into it too. I just need to figure out a filtration system. its a long ways into my back yard. so.. or I can put it closer and put an extension cord to it. I just need to figure out a good free or homemade filtration system. Please help

EDIT: or just something to keep the water clearish and algae down.