I'm baffled too. A 24-oz application of flumi to a .8 surface-acre pond with water-pH7 should demolish watermeal. Likewise, 2x45ppb sequential doses of fluridone should yield reasonably decent reduction of watermeal unless notable water-exchanges occurred during or shortly after either treatment.
What specific methods did you use to conduct both applications?
Would you post a close-up photo of some watermeal spread across your palm, as well as a wide-angle photo of the pond?

Originally Posted By: Algaegrower
0.8 Acres, 4 feet average depth.
Moderate-heavy flow with rainfall, otherwise flow is minimal. rainfall events are problematic with fluoridone)
Spraying clipper w/ Li700 24 oz Clipper was usual dose
Sorry I wrote that wrong I was using Sonar AS, switched to Genesis to see if there were any different results, none. Doing 2 - 45 ppb treatments (.75 gal)
AS was previously 2 - 45ppb treatments as well.
Also no SAV in pond to soak up fluoridone.
Btw there is an added surfactant in genesis that is supposed to enhance fluoridone effectiveness- I have seen this on other ponds. I'm stumped!