Riddle for you!

[Chameleon]

Ok here is the dilemma. I have a pump that is taking water from a reservoir and pumping through a heater at 12.5L/hour at which point it comes back to the reservoir at 100 degrees C. The reservoir is at 25 degrees C. How big must the reservoir be to prevent a 3 degree increase in temperature of the water in the reservoir over 72 hours of continuous use given the specific heat of water is 4.186 j/g degree C? The reservoir is a cube. Would love to see what yall physics/math junkies come up with.

 

[revsgirl]

:bump2:

 

[Chameleon]

I am trying to setup a reservoir for the condensation coils for my double distiller so I dont have to use tap water feed as it builds up impurities in the condensation tubes costing lots of money and time to fix. I was hoping to use ro/di water in a reservoir to feed condensation tubes so no build up would occur, however I want the reservoir to be passively cooled to prevent the need for extra equipment/costs.