destilled water will conduct electricity from the moment it has been contaminated, granted very little, but I don't know how much it takes for the battery effect to be a concern.
without an addittive you still have algea to fight off .... so I would use some innovaprotect or similar, if nothing else, just for the peace of mind ...
__________________
---
eheim 1048, innovarad dual, innovacool rev3, tank-o-matic
xp1900@1750 on a7v333
|