I'm absolutely baffled

[Country joe]

My two tanks are in the same room 4 feet away from each other, my 70 litre tank for months has been constantly sitting at 24c and the other tank at 23c, today I noticed the the temp in the 70 litre had gone up to 26.3 I tried putting the heater down a bit but it remained the same, so I changed the heater to my spare and set at 24c, and replaced the the temp gauge, but after two hours it remains the same, and the other tank is still reading 23c, there is no heating on in the room, and the fluval temp gauge also gives the room temp and its very steady of what it has been, what causing the temp to rise on this tank.

 

[MaloK]

What is the difference between room temp ?

 

[Country joe]

Room temperature.4c 70 litre tank 25.7
Other tank 23.7

 

[Country joe]

Sorry room temperature 22.4

 

[jaylach]

Is one tank near a window where sunlight could affect the temperature? Keep in mind that different seasons of the year could allow more sunlight to make a temperature difference.

 

[Country joe]

Is one tank near a window where sunlight could affect the temperature? Keep in mind that different seasons of the year could allow more sunlight to make a temperature difference.

I keep the blind down permanently

 

[jaylach]

I keep the blind down permanently

Keeping the blinds down would, of course, help but, if the tank in question is near the window sun hitting the blinds could potentially cause temperature issues as there will still be heat transfer just due to the sun hitting the blinds.

 

[Naughts]

Keeping the blinds down would, of course, help but, if the tank in question is near the window sun hitting the blinds could potentially cause temperature issues as there will still be heat transfer just due to the sun hitting the blinds.

So could it be related to the fact that we just changed our clocks? They have gone back an hour so the daylight is earlier.

 

[jaylach]

So could it be related to the fact that we just changed our clocks? They have gone back an hour so the daylight is earlier.

Can't say for fact but that is possible if this gives more potential sun light hitting the blinds.

 

[Archerfish]

but after two hours it remains the same, and the other tank is still reading 23c,

I don't think two hours is enough time to get an accurate reading. Water is much denser than air. I would suspect the thermometer assuming the heater is working properly, and that there is not an overheating powerhead or filter. I would go back to what you originally had and simply switch the thermometers and wait say, overnight to see if the reading are now reversed. If there are no external heat sources (window heat, HV/AC vent) and all of your power equipment is properly working then it has to be the thermometer. One thing to avoid is 'whipsawing' yourself by making radical changes without doing slow, methodical problem solving.

 

[Colin_T]

Maybe the tank with the lower temperature has issues with its heater and or thermometer.

Is there ducted air-conditioning in the house?
If yes, air might be coming out of that and onto one of the tanks.

 

[Country joe]

Thanks everyone , no air-conditioning, being a beginner I maybe panic too much, it has dropped to 25. 7, I will set up some water in a bucket and test out the other thermometer to sit about 24c, it should be okay, as its a decent fluval and is only months old.

 

[Archerfish]

Why not test it under real conditions in your tank? Just switch the thermometers from one tank to the other and see what the results are after about 6 hours.

 

[Country joe]

Thanks everyone I think my panic is over easy sorted, set the the thermometer at 22.5 now temp reading a spot on 24 c

 

[TwoTankAmin]

Thermometers in the hobby are one of the less reliable pieces of equipment we own.

But, we often forget that tank lighting, filters, power heads and pumps, both water and air, heat up when working which in turn heats the water passing through them. Eben the tank istelf can heat the air in a room such that it becomes harder for a tank to dissipate heat into the room.

I have a space dedicate to my plecos which I keep in water between 82 and 86f. I had to have an air conditioner installed in the room which is set at 77 or 78F. Without it, that room would get really warm from the tanks. I also turn it down to work on tanks and back up when I am done. All the tanks in the room have a temperature controller for the heaters.