New to water butts - advice needed

[Tom2006]

Could be the temperature in the butt? Mine is outdoors and the water is always clear, clean and smells like water.

[Dim]

Yep that's what came with mine too, doesn't work

If the connection to the downpipe (or guttering in my case) is higher than the water level then the water just keeps flowing. It WOULD stop, as I expected, IF the lid had an airtight seal but it doesn't.

It has to be 10mm BELOW the top of the butt, see red line on pic. Then when the butt gets to that level it doesn't flow from the downpipe any more