diy gravel vac

I havent seen anything like that at home depot, but i havent looked for it specifically. Youre best bet would be go to a lfs that sells pythons (the gravel vac that uses the sink to drain your tank). They would probably have an attachement like that as a replacement part

its just a waterbed fill kit. most of your hardware store carry them.

Here you go
http://www.ebay.com/itm/like/380370033156?lpid=82

It usually depends on what they carry at your store and what your faucet output size is. Some prefer a screw-on attachment while others a slip-over rubber fitting with metal hose clamp. Not every faucet has a screw on tip either, where the latter attachment works best. Whatever you get, open it carefully as you may have to return it for another size or type of attachment. Not every attachment works for every person. I personally use a slip-on and clamp attachment going to a bathroom faucet w/out threads. When I used to have tanks in the basement, I used the screw-on attachment, because of the ease of attaching to the laundry faucet with a threaded output.