Heat issue in April

[sumpfinfishe]

Ok so I have two hydor 850's in a 33gl long 48" reef running alternatively every minute on a smart wave controller.

I want to run a temp of 78 but with one these two pumps running 24/7 I am getting a temp of 80 and it's not even warm outside yet. The lighting and filtration are not the cause of the increased temp.

My question is should I invest in one MP10?
Will this single pump versus two help reduce heat as the motor is outside the tank, or would changing the alternative flow times more or less of the two hydor's help?