A little conversion for those of us still stuck on the imperial system...

36c = 96.8 F
38c = 100.4 F
30c = 86 F
16c = 60.8

I am taking temperatures from my pond that are very similar...

High ambient temps at my place are in the 90's (F)[32c +]

Low ambient temps at night are mid 70's (F) [21c +]

Pond surface = 90-95 F [32c - 35c]
18" below surface = 85 F [29]
At the bottom at the 7 foot [2.1 m] depth = 76 F [24c]

I don't "feel" like the pond is too hot just yet, but, like you, I only run aeration at night and I monitor my temps most days. I have a small hand dug well near the pond that I could pump water from, but I think the well supply is too small to do any good.

Are you seeing a drop in pond water temperature from using your well?

IF not, I suggest you rethink putting cooler water in the pond at the feed site. You might be risking temperature shock to the fish. This is probably not a big concern, but I would put the well hose somewhere that the fish do not normally hang out at.

If I get to the point that my pond gets HOT, I would try to move my diffusers to the very bottom of the pond. My deepest diffuser is set at 7-8 foot deep where my pond maxes out at 10 foot. This would utilize the cooler waters below the thermocline. I would also monitor for the effect. Other than that, I wouldn't know what more to do...pray a little I suspect!

Fish on!,
Noel