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Fish tank temperature droping - any ideas why?

Ninjascape

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26 Aug 2021
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Hi Iam unsure where this fits into the form but I having issues with my heater one day it's 26 degrees then next day its 24 degrees?
Does any one know why room temperature has stayed the same.
I bought fluvals e smart I left both plugged in for hour then made full switch removing the other heater. To my shock the fuval e smart done nothing ziltch.

So does any one have any ideas what Iam doing wrong?
 

Angus

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Firstly, are they appropriately rated for your tank size?

How cold is the room? the colder the room the more wattage you will need to keep a stable temperature.

Check them inside a bucket with less water volume than the tank but enough to cover the heater fully, measure the temperature of the water with an accurate thermometer, keep an eye on it if the heater is way overrated like say 300w in a 25litre bucket it could melt the side of the bucket if you leave it unattended.

Maybe it arrived kaput? heaters are delicate buggers.
 

Ninjascape

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Hi, yes the tank is 64 liter with a fluval 106 external. I am running 50 watt heater, everything has been fine for months just recently the heaters has been giving me issues I thought it might of been room temperature but that been consistent.
I will test the fluval tomorrow and see if the bucket heats up.
Would a 100 watt heater be to much?
 

Angus

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50w is only slightly underrated for your tank, i would have thought it should be fine in a reasonably warm double glazed room, should only need an hour or 2 in the bucket to see if it's working properly, how are you measuring temps? i would recommend getting a bog standard kitchen meat thermometer if you are a cheapo, or a propper "calibrated food probe" if you want to shell out a bit more, they are pretty accurate from my experience.

Sounds like your heater went bang to be fair, but odd that you have ordered a new one and that seems to be dead aswell, just unlucky? if you can i would just do the bucket test on a free evening, put it on after work, check after 1-2-3 hours etc depending on if its warming up or not.

Do you see an LF instead of the temperature or blue background on the screen on the fluval inside the tank? that would indicate some problems not related to the heater actually working.
 

mort

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I was going to suggest it might be because heaters normally heat to a temperature but then don't come back on till it reaches a degree or so lower (depends on the heater), so you often get a bit of a swing. If the room temperature dips then the temp can swing even more but it doesn't seem the case.

A 50w heater should be fine for your tank unless the room is really cold, which I'm guessing it isn't. A larger heater will help if there is a big difference between room temperature and tank but normally a degree or so (remember displacement from decor) is fine.
 

Ninjascape

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Currently using an aquarium thermometer and stick on one. The fluval e smart was red meaning below 26 degree. It could be the timing on the heater. Going to do the bucket test tomorrow, might just buy a third heater and try it
 

Angus

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Hopefully the bucket test should prove if it is working, heaters are such a nightmare hope you get to the root of it.

If i'm understanding the fluval heaters right (i don't own one) you set the temperature, then blue screen means temp too low, green is just right, and red means too high, this is + or - 1°c for both sides, too high or too low, my heaters are like 0.5 to 2°c out from my thermometer, and i have to calibrate them back to the "actual" temperature i want, while taking into account how far out the heaters thermostat is, so for instance one of my eheim jagers i set at 23°c to get equivalent 24°c tank temperature.
 
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dino21

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One thing not mentioned, is the heater in an area where it gets good water flow all across it ?
Also assume you have it mounted Vertically, Fluval say do not use it Horizontally ?
Our tank is slighty smaller 60lts gross, but happily working with a 100w heater, in a cold room 50w could be pushing it at times.

Same with the thermometers, they need to be in a good flow area, though personally never use the simple stick on types, just to difficult to see which segment is really on.
What about your aquarium thermometer, what type is it and have you compared it against any other to see if its registering properly ?

Also what about your lights, if you are using very strong hot ones that could be increasing the temp by 2c or even too close to a heating radiator, particularly if its a warm room to start with ?
 

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