2 X 200W Heaters Big Enough For A 60X18X24?

[mattlee]

i have forgotten the general rule for heaters and wattage per litre so can someone please remind me?

ive currently got 2 x 300w heaters in a 60x18x24 but have 2 x 200w heaters spare could i swap them over and use the 200w or would it be pushing them slightly on a tank of this size?

 

[minnnt]

1 watt per litre

 

[Tizer]

i got 2x300W in my 425litre...probably get away with a 300 and a 200 though!