0.25 acres is fairly cheap to poison and start over. Which is what I would do...
Trying to keep a balance in a 0.25 pond is a nightmare! I would strongly look into bass that are pellet trained. In smaller ponds(less than a 1/2 acre), utilizing pellet trained fish is IMO the only way to go if you want quality fishing.
Poison the pond, purchase pellet trained bass, keep their numbers low and work hard on keeping their offspring from surviving. I'd remove all cover from the pond to increase predation on any bass offspring.
You can consider other species with low reproductive rates/success that are pellet trained as well to add with the bass.
Just my take on things, but I am far from an expert.
