thats interesting and some thing we never tried. I know that purple loses its colour if you add to much bioside. Its some thing i can duplicate here. The other dyes seem to be fine in the line though but never tryied just leaving them in the open air tbh as every thing is sealed and kept as clean as possible while making the fluids. I might just open the res on one of the pcs thats running purpe and see if it effects it at all... no harm in trying .