If goal is to offset evaporation , on a 5 acre BOW , IMHO , doubt the well water needs oxygenation , especially if entering , say 2-3 feet above water line, the splash will provide some oxygen and the Well water is a miniscule amount of water of a 5 Acre BOW , I wouldn't sweat it. Even if the Well water enters smoothly into the pond. At the end of 24 hours , all the Well water is les than 1 percent of a 5 Acre pond averaging 8' deep. Next, if running 24-7 , better check your flow rate , you could be dropping your aquifer. Mine , was pumping 15 gallons per minute when first drilled , now 12 gpm , 1st 2 hours and then drops to 6 gpm within 5 hours . I've installed 120VAC timers on my two 240VAC Wells , I run on 2 hours , off 4 hours , on 2 hours , off 4 hours , etc. This way I keep my Aquifer up and don't pay for the same Electricity to pump 6 gallons as I do for twelve. Truly , if pumping 40 gallons per minute , that's 57,600 gpm in 24 hours, that's a tad over 1/3rd of an inch per 24 hour period ( Using Jason D's numbers above of 140,000 gallons = 1 inch for 5 Acre BOW ) , over the course of a year, your probably short 1/6th to 2/3rds of an inch short covering your evaporation , even during winter , temperature may drop , but if RH also drops , then evaporation rate may not drop." A lot of depends " on Well water and Ponds. Probably most important thing you can do , keep the Willows and Cottonwoods well away from your pond . Just a guess , but 5,000 little Willows and cottonwoods 2' - 10' tall may suck on average ?7? gallons of precious water per day each , 35,000 gallons of water per day. (A Pondmeister with more knowledge may correct me on the trees and Math ) I hired 4 college boys , with shears , Tordon , and Chemical gloves , working for 4 hours each , and in 24 hours you could clearly see the reduction in water loss , I've never seen the water level gain with my 2 240VAC Wells and 1 Solar Well . My shore line is around a barely 2 Acre pond , and I don't know how many gallons the trees were stealing . Scary how many gallons you may lose to Trees around a 5 Acre BOW. Sorry for my rambling on this post . So to wind up my comments. 1 , Well water probably isn't going to cause an oxygen problem in a healthy 5 Acre Pond. ( Unless pumping more than ?150? gpm ) 2 , Trees affect my Pond level a lot more than my Water Wells . 3 , Beware of your effect on the Aquifer , excessive pumping may hurt you , and may hurt a neighbor who needs the Aquifer for a family , and maybe multiple Families , water supply . Hope my comments are understandable . Oh , 1 more thought , Farmers no longer throw water in the air to irrigate , just wasting water , your evaporating your water that your paying electricity bill for , to replace the water that's evaporating out of pond. Just flow the water into the pond , in 5 Acres , the low oxygen Well water is negligible. ( In 4 years of flowing 2 Wells into my 2 Acre Pond , have never had a problem with Low Oxygen levels . ) (Just started the timers 3 weeks ago ) . If those with true knowledge correct my thoughts and/or numbers , please listen to them , not me.
