The problem with chlorine is that if it doesn't outright kill fish, it destroys their gill membrane. Most fish just can't recover. Once the chlorine has gassed out of your system, you should see about re-seeding it with bacteria. Do you have a neighbor with a koi pond or a fish tank? You can borrow the sponge/filter from that and squeeze the gunk out of it into your beds/filter/fish tank, and that will get things going again quicker than just waiting for the bacteria to repopulate on their own.