"robin.gordon1" wrote in message ...
I have been running my 36" tank for 10 months now and still do not have a
heater present. the temp never varies much more than 1 or 2 degrees C.
is there something wrong in my system. should it be cooler than this. the
ambient temp is around 15-23C but my temp will drop to 24.6C and through the
day rise to 26.7 in the evening. I think a cooler would be more appropriate.
is it my powerheads or return pump or is the MH light heating the water temp
too much.

Add the power consumption of all your powerheads, filters, skimmer pump
etc and imagine you have a heater of the same wattage submersed in the
water which is on all the time... This will explain the issue, I hope...
We do not see the temperature increase so much because we do not use
so much water movement devices...

I still use a heater in my 36" tank - during winter months at night,
when lights do not produce heat, powerhead-generated heat is not enough.