First, I think having an HSB only pond is very feasible. In fact, if you really have no interest in HBG, why stock them? I would consider stocking a few RES as their reproductive rates are minimal and they will shine without competition from any other Lepomis species. If I was doing a HSB/Sunfish pond, I would chose RES over HBG personally. In the absence of other Lepomids, RES will often be easier to catch as they will spread into the niche otherwise taken by BG or HBG.
To control HBG with only HSB, especially HSB that are feeding mostly on pellets there are a few things you should focus on. First is to limit the amount of cover in your pond. It is not needed or wanted... That includes aquatic vegetation, sunken trees, rock piles or other places where YOY or even fingerling F2 and late generation HBG can take cover. Second, before stocking the HBG, you should have the HSB be fairly advanced in size. I would say at least 12" and 16" would be better. This ensures they will have a mouth large enough to effectively prey on any F2 HBG born in the pond. Remember, HSB have mouths that are substantially smaller than LMB for example. Third, there is no need for any additional forage in a pond where HSB are the primary predator of the F2 HBG. Adding GSH or FHM will just mean the HSB will focus more on them and less on your HBG offspring.
To assist the HSB in keeping HBG reproduction under control, CC or blue catfish can be used. In a smaller 1/4 acre pond, just a handful of CC or even 1 blue catfish may be all that is needed. Once the catfish reach 20" or so, they should be removed and restocked with 10"-12" catfish. Unless one really has a desire to grow larger catfish. However in a 1/4 pond, that is probably not the best use of the available biomass.
The use of 1 LMB can also be effective in a 1/4 pond. In a larger pond, say up to 1 acre the use of 4-6 single sex LMB can be used. I would focus on capturing male LMB in the spring when they can be easily sexed. Their growth rates are slower and they should remain in the target size of 10"-15" range for a longer period of time before they should be removed in favor of smaller LMB. The idea is the have LMB that are focusing on removing the 2"-4" HBG F2 offspring. It is very easy to collect single sex crappies in the spring. They may also be an option to help control HBG reproduction in a HSB/HBG pond. Collecting a 1 to 2 dozen all female or all male crappies is not a difficult task when fishing a pond that holds them. Sexing crappies in the spring when they are spawning is very easy.
Most hatcheries offer HBG in the 4" range and some will offer fish up to 6". However, HBG do well in cages and this may be the best method to ensure the fish you release have high survival rates. Keeping them caged until they are 6" and then releasing them into the pond. You can cull out slower growing caged fish in favor of the fastest growing ones. By this size, the few females in the HBG population can also usually be picked out as well, minimizing reproduction by your HBG that much more.
