Hi: This is Jerry from Unique Solutions, the manufacturer of Ahh-Some. Personally, I have never seen any blue or turquoise particulates released after an Ahh-Some "purge". However, nothing surprises me anymore when biofilm and plumbing bio-gunk is involved. Is the blue buildup sticky? Does it wipe off with relative ease? With your white tub the water and shell can take on hues that may look bluish but might not be blue. Lastly, why are you still getting releases after the purge process? Are you adding small amounts of the gel weekly? If not, I think your filter(s) may be responsible for this particulate release. You have to rinse the filters thoroughly after doing the Ahh-Some purge. FYI, we just received a letter from the EPA that our Ahh-Some product is now a registered cleaner. This means that our product does what we say and that we are environmentally responsible.