Hey, Jaymz, welcome to the forum! Really sorry to see that you're faced with this incredibly frustrating issue, too. I feel your pain.
I waited till pretty late in the season to Whitecap my pond, as you probably know from reading this thread. It did work, though, and by late summer, the water was generally pretty clear. My plan is to hit it again in early spring at the time most plants are starting to emerge and try to nail it before it comes out. It's most susceptible to chemical intervention when it's in the growth stage, so hitting it early is better than waiting till later like I did. I don't regret having tried the other products first, but am convinced that the fluoridone is the best way to eradicate this stuff. I am guessing it may take a couple of seasons of chemical treatment to get ahead of it, but we'll just have to see. I am also hopeful that I can get some tilapia into the pond this year at the earliest possible date (hint, hint, hint, Rainman!) just in case they can help, too. In all likelihood, that's going to be at least 30 days apart.
An interesting thing I noted in this pond was that the Whitecap did wipe out all the other vegetation, too, till very late summer/early fall when I noticed some chara starting to grow back. Of course, fluoridone is going to have that effect and what made me notice it was that the YOY BG were getting hammered while we were at the farm as we would see LMB right up on the banks nailing little schools of them. I don't have much other cover in this pond at all and so the YOY fish had nowhere to hide, a situation I intend to remedy this year with at least one area of brush piles near the primary bedding sites. That's a point you may want to consider if you go the Whitecap route.
So, my recommendation, having gone through this now, is Whitecap as early as your growth season allows. Youse guys down in TX obviously have a different growing season than we do, so definitely hit that stuff before it has a chance to really emerge and grab hold again for this year.
Good luck with it and keep us posted on what you do. I, for one, will be very interested to see how it works out for you and may learn something from your experiences that will help me keep ahead on my own place this year.
PS - with that duck out there, you sure that isn't "duck"weed?
