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Gui101do 04-23-2010 06:34 PM

Thermometer reading vs. Heater reading?
I have a 55 gallon FW tank. Right now I have 2 kissing gourami, a featherfin catfish & an electric blue jack dempsey. Their temperature range is upper 70's.

I have 2 thermometers, one at each end of the tank. They both read around 82 degrees. My Marineland 300 watt heater is set to 76-77 degrees and the thermometer attached to it actually reads about 75 degrees.

Which reading do I take as fact? What's going on here?

Greenmaster 04-23-2010 07:05 PM

If the thermometers at the ends of the tank are submersible then I would say they the thermometers are right and your heater is toast. I would get 2 new ones... 150W because it's always safer to have 2 150w then 1 300w (if one fails then there is still heat... and if it fails the way you are saying then it's harder for it to cook your fish)

mfdrookie516 04-23-2010 07:09 PM

alot of times, heaters and thermometers dont read the same. mine is that way. i have a 300w marineland stealth pro in my 150g... i have the heater set on 76 but the temp of my tank is always 78. I'd say go off the two on the sides, and if it's consistent, dont worry about it

Greenmaster 04-23-2010 07:18 PM

Ya you could go that approach... turn your heater down a few degrees and monitor the temps closely.

Gui101do 04-23-2010 07:24 PM

The heater shouldn't be broken, it's only about a month old.

Well if the thermometers are correct & the heater's reading is wrong, then I should turn down the heater even more? Right now the heater is set to 76 & the thermometers read 81, so if I lower the heater to 74 or so, my temeprature should be about right.

Greenmaster 04-23-2010 07:37 PM

As long as it's not the sticky thermometers that are on the outside of the tank I would go with the thermometers. I would turn it down and watch temps closely, but first we should see if maybe it's something else that is the problem.
How is your water circulation?
What do you have for lights/other things that could heat the tank?
Is your tank close to a heat vent or a baseboard heater?
What is the temp of the room?
Is the tank near a sunny window?
Is there anything else that might affect the temperature?

Gui101do 04-23-2010 08:02 PM

They are two regular glass thermometers.

I have undergravel filter trays with two powerheads attached to the up-tubes. I have the powerheads pointed to spray from the corners towards the center of the tank.

I have a few plants in the tank, just some low-mid light things, so I keep the hood lamp on for around 6-8 hours a day. It's just the basic Marineland hood and bulb to fit across the 4 ft length.

Vents and windows are not near it. Room temp is low 70's.

mgamer20o0 04-23-2010 08:57 PM

sadly it seems the quility of the Marineland heaters been slipping. i know of a bunch of people with problems with them. go with the glass thermometers.

Greenmaster 04-24-2010 03:23 AM

But for now if you don't have the money (or don't want to spend it) I would go with mfdrookie561's suggestion and just turn the heater down 2-6 degrees till your thermometers read the temp that you would like in your tank.

DragonFish71 04-24-2010 11:20 AM

Or just go to Walmart and pick up a thermometer for very cheap. The glass ones are about 1.99.

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