Thanks everyone for your thoughts. I am fair confident it is not mold (bottles are still nice and clear, even the funny tasting ones). It could be metabolism as the first run seems to be more impacted than the second run. They kind of blend together.... I don't have the best system down yet still ironing out the kinks! The other thing I was thinking of is this is my first year with a homemade RO system and it is possible I did not clean the membrane well enough. Lots of big plans for this year, fingers crossed for a good run. Thanks again, as a new guy I appreciate the insight of you folks who have so much more time in the field.