Coop heater problem?

[Twigflinger]

Hey guys.  I just ordered the 100 watt heater and am testing it in a cold garage in a 20 gallon tote to see if it will maintain temp.  I have a small filter running for water circulation and a plastic lid.  To help hold in heat.  This morning the heater read 81 however a mercury thermometer I dropped in yesterday reads 70.  I have not read anything yet about the heater being that far off in accuracy.  Could the mercury thermometer be inaccurate?  Should I just set the heater to 91 and see what happens.  I am doing testing to see if I can maintain water temp as I need to move betta fry to the garage for more space.  I do plan on adding a second heater as a backup in case 1 of them fails.  What do?

[Pepere]

I have gone in to a store to by a wall thermometer before and noticed the available thermometers for sale might have widely varying reporting on the shelf.  Presumably they are all being exposed to the same temperatures….

 

And of course the Co op thermostat could be off as well.

Another thermometer might be in order for confirmation.

Personally I can tell the difference between 70 and 80 degree water easily enough by immersed hand.

as to tote in a cold garage, I would be tempted to place that tote on a square of foam insulation board at the very least to avoid conductive losses to the floor.  I myself would build a foam box to sit the tote in with a well fitted foam lid to reduce heat loss. But I am a big big believer in insulation and efficiency..  If I have the choice of a bigger heater or better insulation I am strongly biased to the more insulation route.

[Twigflinger]

Good point.  I will try putting my other heaters in and see what they read.  I do intend to insulate around the tub as much as possible with foam board and maybe some of that thin shiny aluminum looking insulation stuff.  This is certainly not the expected use case for an aquarium heater and I’m sure it will affect its lifespan.  

[dangerflower]

I like to have a probe thermometer (like the kind used in kitchens) on hand for verifying water temps. You can check the calibration in ice water to make sure you're getting an accurate read.

[Twigflinger]

Dang..  So i put in one of my other heaters and it is reading 75 while the coop heater was reading 88.  75 corresponds exactly with the mercury thermometer.

[Twigflinger]

Problem solved I think!  All a matter of water flow.  I swapped it to a bucket back inside and it was reading correctly.  Took it back outside and placed it in the tote and watched it.  temperature rose to 85 which is what it was set at then kept climbing.  I moved it up against the filter intake and watched numbers fall back to 85.  It seems I simply underestimated the amount of flow it needed to work properly?  I am going to continue monitoring though.  I dont understand how in a 14 gallon tote the water temp would not all equalize?

[Pepere]

I have mine right near the subtsrateof the tank.  I run under gravel filters.  A digital thermometer with the probe at the top corner of my tank is in full agreement with the aquarium co op heater digital readout…

 

by keeping heater at bottom near substrate I can do a 50% water change on a ten gallon tank and not have to worry about the heater getting exposed.

 

perhaps if your heater is near top of 5e tank convective currents are not as usefull as having at bottom of water column…

[Twigflinger]

I agree.  It is laying flat on bottom and up against intake now.