You're right about alkalinity, PH and hardness being the biggest consideration. And, I expect that you're right about needing to drain and start over. That's easier said than done. If you drain it, you will find quite a few ft of pudding like mud. It has to dry before being removed and that takes time and hot, dry weather. Don't get in a hurry. Fix the house first. You might want to spray the trees first and kill them. For that I use Remedy mixed 1:4 with diesel all around the trunk.

It is sometimes easier to just dig another big hole above it. If there's any dirt left over, dump it into the existing one.

How big is the property? If big enough to justify it, get a couple of 4wheelers to get around on. Add a shipping container, with a covered lock, to keep them from being stolen. That way, the Grandkids will visit. Since I'm spending your money, a 30 or 40 horse tractor with a loader and 4wd will be a purchase that you won't regret. A tractor without a loader is only good for farming. And, a loader without 4wd is useless.

It's not about the fish. It's about the pond. Take care of the pond and the fish will be fine. PB subscriber since before it was in color.

Without a sense of urgency, Nothing ever gets done.

Boy, if I say "sic em", you'd better look for something to bite. Sam Shelley Rancher and Farmer Muleshoe Texas 1892-1985 RIP Grandpa