But you added O2 to the pond water when it went from the pond to the bucket. \:\(

Bore a big hole and with your hand and arm stick a separate bucket down into the big hole 18 in below surface -- wait 1 min. and remove. Set the bucket down on the ice while you chip off the ice from your ice encased arm and hand - then do the test above and check BDO test for results - no bias in this method. It does carry a strong risk of frostbite however. \:D -- ;\)