How Long Should It Take To Heat 5 Gallons?

I just set up a Fluval Spec V, and based on recommendations I found online, I got a Hydor Theo 50 watt heater. I turned on the heater almost two days ago, and it still hasn't reached the right temperature. How long does it normally take to heat a small tank?

I started with the heater in the filter pump compartment for around 5 hours, but moved it to the main tank since the heat wasn't spreading to the main tank. The plan is to move it back to that compartment once the water reaches the goal (80 degrees), and hope that it's able to maintain the temperature.

The water started at around 50 degrees according to the cheap glass thermometer I got. Moving the heater to the main tank definitely helped but after a full day it had stalled out at around 60 degrees. So tonight I changed the heater setting from 80 to 85, removed some water, and replaced with around 3/4 of a gallon of warm water. That brought the temperature up pretty quickly to 68 degrees, but it's since dipped back down to 66.

Is it normal for a 50 watt heater to take multiple days to heat 5 gallons of water? That seems like a really long time... I'm concerned it won't be able to reach or maintain a high enough temperature, since I'm planning on getting a betta. Should I do a bigger water change with warm water? Or just give it more time?

 

It seems as though it’s not a strong enough heater, if you can turn it higher then try that first but if that doesn’t work then you should buy a new heater, can you return it for a defect? If not don’t throw it away because it may come in handy in an emergency

 

Thanks - you're right that it might be defective. It definitely is turning on and off and producing some heat but it doesn't seem as strong as it should be. I'll turn the heat up again and see if that makes a difference.

I guess it's also possible that the thermometer isn't accurate, but I'm not sure what to do about that since if I get a different thermometer, how will I know if that one is accurate? The water doesn't feel warm enough to me so I'm inclined to believe the thermometer, but I don't want to rule that out.

 

Thanks - you're right that it might be defective. It definitely is turning on and off and producing some heat but it doesn't seem as strong as it should be. I'll turn the heat up again and see if that makes a difference.

I guess it's also possible that the thermometer isn't accurate, but I'm not sure what to do about that since if I get a different thermometer, how will I know if that one is accurate? The water doesn't feel warm enough to me so I'm inclined to believe the thermometer, but I don't want to rule that out.

In my 60 gallon tank I bought a heater that was rated for my aquarium, it wasn’t quite sufficient, if I want the water to stay steady at 80, I have to set it to 90, this could just be a defect but from now on I’m buying a heater the next size up, I would recommend just buying a new heater, one for a 10 gallon shouldn’t cost much off of amazon

 

How cold is the room? While heaters are sold based on tank size, that's only when the tank is kept in an average room temperature of 70 degrees. If the room is cold then more watts per gallon are needed.

 

The house thermostat says it's 69 degrees, but my room is usually a little colder than the main house. It's also right next to an external wall, and there are (covered) windows nearby...

Still, I thought I was playing it safe by getting 50 watts instead of 25. Not sure how much stronger would be safe for only 5 gallons. I'm also limited by the size of the filter pump compartment which is not that big, I'd really like to keep the heater tucked in there and the one I have now is the perfect size. I guess I'll see if it gets any warmer overnight and weigh the options in the morning :/

 

It shouldn't take any longer than an hour if the heater is sufficient otherwise it's going to constantly be struggling.

 

I just stuck the thermometer in a glass of crushed ice & water and it's wildly inaccurate; it's registering at least 15 degrees below freezing (the numbers don't go down that low so I can only estimate). So, I think I need to shop around for an accurate thermometer instead of worrying about the heater right now. Turned the heater back down to 80 since it's probably doing an all right job, lol.

 

Lol, sometimes we forget the simple things! I have a digital meat thermometer that works great. I got it from amazon for $12. I just have to be careful I don't jab a fish with it.