temp problem

[min12512]

in the past week my temp has risen from 79 to 84. i dont have a chiller but now i have a stand fan blowing which has kept the temp down. i have a glass canopy for my 90 gallon f/o tank. last night i left the glass canopy open with no fan blowing and the temp went from 82 to 86.5. please help. please respond i need help. also how long is it ok to keep the fan on?....as long as the temp is down?

 

[nereef]

what kind of lights do you have? also how far are they suspended above the tank?

 

[lorab]

I don't know what kind of heater you have, but mine has a way to adjust it... sometimes heaters get hotter right before they "go out" or "short out"... it can be a good indicator to buy a new one.
:notsure:

 

[zanski]

TURN DOWN YOUR A/C!

do a small water change that should bring down the temp a little. turn the lights off for 24 hours and see where the temp is, if it goes back down then can you raise your lights? if not in the summer reduce the usage of your lights if possible.

 

[salty cheese]

FWIW
I keep my temp between 82 and 84.
IMO I would get rid of the glass top, it prohibits gas exchange and evaporation.
The best method other than a chiller to cool your tank is through evaporation. :happyfish