I would like to share my experience that I had with a Peltier element to cool down the water in the basin.
During our hot ‘indian-summer’ the water temperature raised to 30° C. That was when I started thinking of a way to cool down the water temperature.
I ordered a Peltier DIY kit from china and connected the cooling elements to the circulation pump int he water (this one)
Here you see some images of how this looks like:
As you can see, it comes with 2 heatsinks and small fans.
The total power consumption of this device is around 70 Watts ( 6A @ 12VDC)
I started to measure the water temperature just to find out that the water temperature actually increased (!) after a couple of hours…That made me thinking and exploring.
I found out that the Peltier elements are actually very inefficient: around 10% effective. That means that 70Watt of energy consumption leads to 7 Watts of effective cooling.
The pump in that basin needs to run during the cooling in order to avoid overheating of the element. But this pump is submerged so it actually heats up the water, either by heat exchange or by icreased entropy. This is a 7 Watt pump !
So my conclusion: Using Peltier elements to cool down the water temperature is highly inefficient.