if you're using the pvc
cement used to glue the schedule 40 and scedule 80 pvc
pipe together.. comes in a metal can usually... I beleive the brand is oatey or something.... could be others too I guess... but if you look at the back of the can there will be some information about using it in "potable water supply"... if it says that then you're using the right can of PVC
cement... if it doesnt you picked up the wrong one... there isnt any sort of "anti-mildew" additives in it but it's more a matter of other chemicals in it that could break down during exposure to some of the stuff we put in our tanks etc...
colors of pvc
pipe doesnt really matter... nor does the color of the glues used... but you have to be sure it's for drinking water use for the glue... not the ones that can only be used for things like sewer and stuff....
that whole 100% silicone (with mildew fighter) thing is kinda funny... shouldnt it be 99.999999% silicone 0.000001% mildew fighter? I guess it's kinda along the lines of the Smuckers 100% fruit spread thing because some "weird people" dont think "Fruit Pectin" counts as fruit.... so they shoulda done the 99.99999% fruit...
(there was a news story where some "consumer advocate with a sensitive sense of taste thought her fruit spread didnt taste 100% fruit..." so they sued Smuckers because it says things like various fruit juices.... fruit pectin.... etc... all derived from fruit ingredients... so her beef is that it isnt 100% fruit of what she's probably looking at the label where it says Strawberry or something and it's got pear juice and some grape or something in it as well as the strawberry? Plus that "fruit pectin thing" which... is a fruit thing too.... *Shrug* just a california thing I guess.... oh well..)
ANYWAY.. the silicone thing is unfortunate and I believe it would be advisable to either disassemble and scrape off the old silicone and redo it with non-additive silicone... or build a whole new one. PVC
.. look at the label for "usable in potable water" or something like that"