Water Temperature is HIGH... ?

I have a 300 gallon preform. It get 4 hours sun. But its above ground
and when its 90 the water iis 80... How high can it go before the comets
and koi and turtles have a problem? I was told 85 or under is ok. But
what happens if it goes above 85? Is there any ideas to keep the temp
around 80-.? The bottom of the preform touches the ground. So I thought
it would be ok. The in pond pump is 200 watts and also a 20 watt light.
Does the pump put out heat also? Thank you