Phil, welcome to PB. A couple of initial thoughts.
I'm not sure I would do much of anything. I'd probably add 5 or 6 grass carp to cut back a little on the APW but not more than that. APW, in the proper amount, is a pretty good thing. If they start really eliminating it, I'd use a shotgun on a couple of them.
I agree on tilapia and have, in the past, paid about $10 per pound for them. They will die out in winter so will have to be restocked every year.
Your alkalinity is awfully high but I don't see a problem with it. I expect some limestone must be in the area.
The horses will add some nutrients but their droppings are mostly compressed grass due to their inefficient gut. If it were cows with that alkalinity level, it could be different.
Other than targeting the crappie for removal, there's not a whole lot I would change at this time. Your forage base sounds good if they are in different sizes. You're catching 3-4 pound bass which appears to be your goal.
I'd fish for the catfish and see how they are doing.
Make or buy a sechi disk to check on the clarity. This will identify the phytoplankton base. Phyto is the basis of the food chain for the pond.
At this time, I dang sure wouldn't fertilize.
Your best tool will be a log of all fish caught and general observations.
Last edited by Dave Davidson1; 03/23/14 07:02 AM.