Is RO-DI safe for washing filtration media?

[W0terMoist]

Will washing bio balls and or filter sponges in RO-DI kill the beneficial bacteria?

 

[gbroadbridge]

Will washing bio balls and or filter sponges in RO-DI kill the beneficial bacteria?

Probably, but most (probably >99%) of the bio filtration in the tank is done by the live rock if you have it.
If you need to rinse bio balls just use water change water.

 

[Tlledsmar]

Likely. Use old tank water. I'd go a step further and rinse half now half later