Heat gains

[marc5180]

Hi all, I'm trying to work out how to cool 250 litres of water from 30°C to 25°C for an aquarium fish tank but im struggling to work out the cooling load.

I'm using the formula Q = m c dt

m = 250litres = 250kg
c = SHC for water= 4.19kj/kg
dt= 30-25 =5°C


Thinking of using a plate heat exchanger and a pump that will deliver 0.25kg/s through the exchanger ( this figure will change once i fully know i have the formula correct, its theoretical for now)


So we have :
0.25kg/s
4.19kj/kg
5k

So Q = 0.25 x 4.19 x 5 = 5.2kw.

This will complete the water cycle in 250/0.25 = 1000 seconds or 16.6mins

I understand that by reducing the mass flow rate this will decrease the cooling capacity but even still i thought these aquarium coolers are normally in the Watts range and not the KW, like i have calculated.