dude chill out, we have koi ponds with show fish worth £800+ so i know how care for ponds. i have been swimming in my pond it is that clean. however i still would not put pond sponges into my aquarium filter. Especially in this country
1) you may have had diseases that you may not know about. (esp as someone suggested asking someone else if you can borrow some of their sponges!)
2) as the pond is outside, there may be 'air borne' spores and other things in the water and therefore on the sponges.
3) looking inside my pond filter box i would not want that in my aquarium! id rather ask a trustworthy person or friend if i can use their aquarium sponges.
water quality is as good if not better than an indoor aquarium perhaps but its not just this, it is what comes in on the sponges.......
LINK HERE, READ IT
i personally would not want all of these 'creatures' in my aquarium however small they are. id rather wait for cycling to finish and go and find some ammonia.
/www.fishforums.net/index.php?showtopic=150631
little Pleco! 
