Fish tank rocks for medium ?

I never done hydroponics but i was wondering can I use my fish tank rocks for a medium to hold my plants I have alot of old ones that i rinse and use the water for my house plants couldn't i just use them? Not sure if i even going to try hydroponic i was just wondering in general.

Yes you can use them. I've seen a friend use nothing but fish tank rocks for a grow medium in all his plants.