I turned around my old refurbished pond (that was over run with GSF) in a couple years by simply stocking a few hundred 3-5" BG that were too big for the GSF to eat. Now BG dominate the pond with modest levels of GSF still present.
I was fortunate that I had a surplus of that size BG from my main pond to transfer so did not need to buy any of the more expensive, harder to source, larger BG.
The larger BG are more expensive to buy, but if I had a GSF problem pond and needed to stock BG, I would much rather buy a few hundred advanced size BG over say 2000 2" BG. The larger BG would not get eaten and would soon be pumping out tens of thousands of BG fry.
