Water temp

[orangepunkins]

I have an issue that should NOT be happening. I have a 75 gal tank with glass lids and a canister filter and I'm in my last week of treating for ich. What I have done is up my tank temp to 86 degrees. And I'm also using a herbal ich treatment. Now here is the issue: during the day the temp is 86 with the lights on. After the lights go off within 1-2 hrs the temp of the tank jumps UP 2-3 degrees more. Strange I know. My husband says when the lights go off maybe the temp should go down no up. So now my tank is 88-89 degrees after the lights and the plants are melting and the fish are getting figgity. So I lower the temp in the day to 84-85. Same thing after the lights go off the temp of the water jumps up to 86-87 degrees. Very strange. The heater is a marineland glass heater is about 1yr old. Anyone else have this issue?

 

[PA Pat]

are your heater and lights on the same circuit breaker? run an extension cord to another outlet that is on a different circuit in the house and monitor what happens. Sounds like your lights are creating a draw on your electric that reduces the effectiveness of your heater. put your heater or light on the extension cord and see if the fluctuations continue.

 

[ScotJudd]

Another thought. If the lights are heating the water at the higher level, where the thermostat of most heater/stats are situated then the stat might be affected and keeping the overall tank temp lower than at night when no other heat source is present. You could ensure that water flow across your heater/stat is good.
I had a problem with my tank where one heater/stat was at one end of the tank by a cold external wall and the other at the end that caught the sunlight. They were fighting each other and the tank temp was not reliably stable. I now have a digital temperature control box with a probe at the back of the tank, half way along and half way up (if you get my drift). The box switches on and off both heaters and my tank temperature has become very stable. I got the box on the Internet for about £15.00.



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[mikem691]

Another thought. If the lights are heating the water at the higher level, where the thermostat of most heater/stats are situated then the stat might be affected and keeping the overall tank temp lower than at night when no other heat source is present. You could ensure that water flow across your heater/stat is good.
I had a problem with my tank where one heater/stat was at one end of the tank by a cold external wall and the other at the end that caught the sunlight. They were fighting each other and the tank temp was not reliably stable. I now have a digital temperature control box with a probe at the back of the tank, half way along and half way up (if you get my drift). The box switches on and off both heaters and my tank temperature has become very stable. I got the box on the Internet for about £15.00.
View attachment 249218


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I agree with this 100% has to be the issue

 

[gilpi]

Another thought. If the lights are heating the water at the higher level, where the thermostat of most heater/stats are situated then the stat might be affected and keeping the overall tank temp lower than at night when no other heat source is present. You could ensure that water flow across your heater/stat is good.
I had a problem with my tank where one heater/stat was at one end of the tank by a cold external wall and the other at the end that caught the sunlight. They were fighting each other and the tank temp was not reliably stable. I now have a digital temperature control box with a probe at the back of the tank, half way along and half way up (if you get my drift). The box switches on and off both heaters and my tank temperature has become very stable. I got the box on the Internet for about £15.00.
View attachment 249218


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Pretty good observation. The heater's thermostat senses the light's heat which is warmer than the temp it's set at, shutting it off.
I'm curious, would moving the heater down deeper into the tank work?

 

[mikem691]

Pretty good observation. The heater's thermostat senses the light's heat which is warmer than the temp it's set at shutting it off.
I'm curious, would moving the heater down deeper into the tank work?

If its fully submergeable it might.

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