29 gallon help

[truck_317]

so i got this good deal on a 29 gallon tank tonite. i payed 20 bucks for it. i have alot of cleaning work to do to it to make it ready to use. the tank came with a old aquatech power filter but i dont want to use it. i am looking at using this tank for a fry tank and i want to put a sponge filter in it from ati. i was looking a a 80 gallon sponge, should i get 2 of them so i have better filteration or would one 80 gallon sponge be good enough. so guys and girls please put any info on here to help me out thanks