Got it done per Cary. THANK YOU CARY!
Diffuser is at 4 feet set for a 1" boil. It is elevated above the bottom so not in muck. I suspect this pond has muck on steroids as its old and has about 20 small sweet-gum trees at its shore in 2 places. Will follow thru with the rest of Cary's advice.
The good news is I only found 3 more floating dead, after following Greg Grimes' advice to shut it down Sunday. Sounds like semblance of breakin I did saved me and have dodged a bullet.
Still feel dumb on ponds, but less paranoid. Sure wish I lived there.
