I finally found some things around the house that would be neat for my bettas homes, but all of been washed with soap in the past and used a lot. Should i just buy new things, or is it possible to disinfect these items so i can treat my kids? :D
I'd assume the water / bleach, or water / vinegar solutions would work and remove any residue, bacteria, etc. I think the last time I read something on this from people on this forum they were using like 1:20 dilutions, but you can't hold me to that.
There would also be other aspects of using household items rather than just removing soap. Like making sure the paints aren't harmful - or rather, anything in the item. I would be too scared to use household items because I'm not 100% sure what it's made up of. That would be my only scare-off.
Soaking for a week in fresh water can likely remove any soap or residue. However, it may just be best to purchase new products that haven't been introduced to chemicals. Then again, if it wasn't made for an aquarium, you never know what chemicals it has been introduced to.