I went through almost a dozen emeralds in my quest to keep the stuff under control. They weren't very useful at it. Frankly I wonder if the problem is that it's a little like trying to drain a lake with an eyedropper. Perhaps you can eventually get "lucky" and get one with a ravenous apetite for valonia but the methodology of buying them again and again in the hopes you'll find that one seems pretty ineffective to me.
I think if something like a rabbitfish or a tang isn't an option then realistically the only option is aggressive manual removal. When removing from rocks, take the rock out of the tank to prevent the stray scruboffs from floating away. As far as the glass is concerned, I guess remove carefully from there and try to get every last bubble that gets away. Any equipment that gets it, same deal as the rocks, take it out, don't try to clean it in place. I learned this the hard way and it actually was a deciding factor for me to take down my 90g a couple months ago, I just couldn't keep up. I even had these gargantuan mobile/roving colonies of valonia (turned out to be astrea snails underneath).
Those big marble ones seem to be not too bad, it's the little ones that only get to a couple mm in size that are a serious problem. I'm not sure if it's a different species or what, but it's the little ones you really need to panic about. Seriously, once it gets past a threshold you'll find yourself fighting a losing battle so don't let it get away from you.
Maybe another option is to see if you can find someone with a valonia eater and temporarily (or permanently) trade rocks or something like that.
Good luck!!
PS. I found that for equipment like heaters, powerheads, seios, whatever, etc. etc. -- soak them in vinegar for a little bit. Works like a breeze!!!