Just got back from the cabin and have some data to share. When I first collected the DO readings I was a little disappointed. They seemed awfully low for what I was expecting. When I put them into the spreadsheet and compared to 2017 they don't seem as far off as I thought.
Keep in mind, in 2017 I was running a 1HP pump the produces much higher CFM. All I have been running in 2018 is a 1/2HP Thomas 2660. I have been running the 1/2HP for longer duration than I was running the 1HP.

I am wondering if anyone can tell me why my surface DO goes so low in September both years? In 2017 it seemed to climb back up as we got later in September and the water temps dropped. I understand DO will rise as water temps fall, but shouldn't my surface DO have been rising from July/August since my water temps are down 20 degrees? In July and August 2018 my surface DO was at 8 & 9 PPM. In July and August 2017 surface DO was at 9 and 10 PPM before I started running aeration.

I am confused.

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