You can... One caveat to the above, you need to make sure that whatever you use is not treated with an anti-bacterial chemical or pretty much anything.
I wouldn't use straws because of the likelihood that they would flatten and block water flow,
PVC would work, but I would use the smallest thickness possible and cut to as short a length as possible.
But again.. not terribly porous.
If you are looking for something around the house that is cheap and easy to get, maybe look at plain pot scrubbers, it will have much more surface area than something more 'hard'