Fluval Spec V Owners - What Heaters Did You Use?!

Hey guys,

I know a lot of people struggle with the age old question of what heater fits into the compartment of the Fluval Spec V (5 gallons). I would love to hear from owners who have successfully fit a good quality heater into the compartment and been able to heat up the water accurately and made sure it remained stable.

My plan is to puncture some small holes in the output pipe in the compartment which I have seen recommended by many to make sure the heat is spread evenly. I originally had my heart set on the Eheim Jager 25W which apparently was sufficient however I've read reviews saying it does not fit.

I've heard of three main heaters which are able to fit in the compartment so far:

• Hydor Theo
• 25 watt and 50 watt)
• (50 watt)

I would also love to hear people's opinions on which wattage to use for a 5 gallon tank such as this and what they've found worked. I am housing one Betta fish so the temperature needs to be around 26 degrees celsius (between 78-80 degrees Fahrenheit). Ive heard people use both 25 and 50, but 50 sounds like the safer option. Once again I'm not sure!

Any recommendations would be helpful to help me decide! I have been researching this for weeks and every time I am set on a heater I see a bad review/change my mind! I would love some personal recommendations so I can finally order it and decide what to get. Bonus points if I can ship it/buy it in Australia Thanks!

 

I used a Hydor 50 Watt in the back outtake compartment for a while at the recommendation of a YouTuber (SolidGoldAquatics) but I think her link led me to the wrong wattage. I should’ve got the 25 watt. I had to increase the temperature on the dial past my set 80 degrees to around 85-87 degrees. It worked for a while but I didn’t trust the heater running at nearly 90 degrees while sitting on my outtake tubing because I got a heater that was a bit too big. Maybe that’s just my anxiety getting the best of me but I moved it in to the main portion of the tank. The 25 watt would probably fit and work fine.

 

I used a Hydor 50 Watt in the back outtake compartment for a while at the recommendation of a YouTuber (SolidGoldAquatics) but I think her link led me to the wrong wattage. I should’ve got the 25 watt. I had to increase the temperature on the dial past my set 80 degrees to around 85-87 degrees. It worked for a while but I didn’t trust the heater running at nearly 90 degrees while sitting on my outtake tubing because I got a heater that was a bit too big. Maybe that’s just my anxiety getting the best of me but I moved it in to the main portion of the tank. The 25 watt would probably fit and work fine.

I’ve heard mainly good things about the Hydor! Although one thing I have noticed is some recommend the 50 and others the 25, so I’m with you there! Did you move it into the main display more because it was too big and you were scared of it grying the tube, or because of heating issues? I’d love to know if you’ve had any issues with the actual heater itself still unsure if I should go for the 50W or 25W myself! Thanks for your response!

 

Ive had the recommended Fluval heater for that tank in mine for over six years. I don't remember the wattage and the sticker is long gone...but I'm guessing it's a 10W preset heater. Temp stays stable and I check the heater every month and it is still working, however I do not know what the exact temp of the tank is.
There is no need to modify the tank to disperse heat. The Fluval heater will fit in the compartment with the return pump, and therefore the return pump will draw the warmed water into the tank. If you poke holes in your return compartment, you are going to draw water in through those holes because of the suction of the return pump and you'll be bypassing the filter. For a betta, that tank is just fine the way it is, and very well designed.
It is tempting to oversize your heater, but remember, aquarium heaters do not fail "off" they fail "on"...so you put a 50W heater in a 5 gallon tank, which is total overkill, and in five or six years when that puppy fails you have betta soup.

edit one more thing...
one modification you SHOULD make for a betta in that tank, is get a prefilter sponge and put it over the output nozzle.

 

If it’s the newer fluval you can just turn the flow down and it’s not an issue for bettas. I tried a pre-filter sponge and it baffled my outtake too much.

I moved it because it was too big and it took some work to get in to the outtake compartment. I didn’t want it cracking the outtake tubing either, but it probably would’ve been fine. I would go with the 25Watt I wanted to return mine but I was already buying it as a replacement and I needed my tank heated. I’ve had it for over 2 years now and it still works great. It’s a little off though, I have it set to 85 and it maintains my tank at 80.

 

I use a Tetra HT10 50w preset heater for my Fluval Spec III (2.6g). It's in the pump section and works great. It keeps my tank at 78°F as measured with a infrared thermometer.

 

I use a Tetra HT10 50w preset heater for my Fluval Spec III (2.6g). It's in the pump section and works great. It keeps my tank at 78°F as measured with a infrared thermometer.

Thank you! That is what I am looking for, a heater that fits the tank. I may have not made myself clear to all the others. I

 

Most of the heaters mentioned should fit in the pump section. The one I use is just the cheapest because it's non-adjustable. If your stock is ok with 78°F, I can easily recommend the HT10. If you need adjustability, the Aqueon Pro 50w is a great choice.

 

This is the one I use:

It fits in the Spec V

 

I agree with your points here. I have been challenged to find a heater that fits inside the side space nest to the filter in the Spec V. I also want one that puts out enough heat to keep my Betta comfortable. I will keep an eye on the replies your receive in this thread.

If it’s the newer fluval you can just turn the flow down and it’s not an issue for bettas. I tried a pre-filter sponge and it baffled my outtake too much.

I moved it because it was too big and it took some work to get in to the outtake compartment. I didn’t want it cracking the outtake tubing either, but it probably would’ve been fine. I would go with the 25Watt I wanted to return mine but I was already buying it as a replacement and I needed my tank heated. I’ve had it for over 2 years now and it still works great. It’s a little off though, I have it set to 85 and it maintains my tank at 80.

Have you tried the sponge on the filter outflow?

 

This is the one I use:

It fits in the Spec V

I have 5 Fluval canisters, (206, 2x 306, 406 and FX4) as well as Plant 2.0 48" and 3.0 36" lights. I love Fluval but their heaters are way overpriced for what they are. For adjustable heaters, the Aqueon Pro is possibly the best you can buy regardless of price. I've been testing a few different heaters and the HT10 is a great, inexpensive choice if you're ok with a preset heater. I bought 4 in the last year for QT, brine shrimp hatching, warming up RO water for my shrimp tank and other temporary needs. It fit perfect in the Spec III so it's been in there for over a year w/o issue. I haven't modded the Spec III and it keeps a steady 78°F in the tank.

I've tested Cobalt and Finnex heaters and they're good but too bulky. I have about 10 Aqueon Pros and a few regular Aqueon heaters. The regular aren't that great but the Pros are flawless. The newer models (LED on control knob) aren't as good as the older one but still pretty good.

 

Ive had the recommended Fluval heater for that tank in mine for over six years. I don't remember the wattage and the sticker is long gone...but I'm guessing it's a 10W preset heater. Temp stays stable and I check the heater every month and it is still working, however I do not know what the exact temp of the tank is.
There is no need to modify the tank to disperse heat. The Fluval heater will fit in the compartment with the return pump, and therefore the return pump will draw the warmed water into the tank. If you poke holes in your return compartment, you are going to draw water in through those holes because of the suction of the return pump and you'll be bypassing the filter. For a betta, that tank is just fine the way it is, and very well designed.
It is tempting to oversize your heater, but remember, aquarium heaters do not fail "off" they fail "on"...so you put a 50W heater in a 5 gallon tank, which is total overkill, and in five or six years when that puppy fails you have betta soup.

edit one more thing...
one modification you SHOULD make for a betta in that tank, is get a prefilter sponge and put it over the output nozzle.

Thanks for your response! Honestly a lot of these responses are making me more confused than ever I've heard from almost all Fluval Spec V owners that the best possible way to heat the tank without placing the heater in the main display is to puncture small holes in the pipe. For example, a lot of the information about this tank I have received from this website which is completely dedicated to spec tanks, I'll include the link here: With your experience with the Fluval Spec, do you recommend not making any modifications? Definitely going to add a baffle for the filter though!
I've also seen so many different aquarium companies recommending different wattages for different gallons. The general consensus seems to be 50W for the Spec V however reading your comments I think you might be right.. always better to be safe than sorry! Would you recommend just a 25W for keeping a Betta in 5 gallons? I live in Melbourne Australia, not sure if that helps give everyone an idea of the weather

If it’s the newer fluval you can just turn the flow down and it’s not an issue for bettas. I tried a pre-filter sponge and it baffled my outtake too much.

I moved it because it was too big and it took some work to get in to the outtake compartment. I didn’t want it cracking the outtake tubing either, but it probably would’ve been fine. I would go with the 25Watt I wanted to return mine but I was already buying it as a replacement and I needed my tank heated. I’ve had it for over 2 years now and it still works great. It’s a little off though, I have it set to 85 and it maintains my tank at 80.

Wow that's so interesting! So you don't use a baffle at all for your Betta and he can swim okay? The one I purchased is actually the newer Fluval, so hopefully it will be okay. However I am ready to reduce the outflow if need be! Thanks so much for your help, I'm actually leaning towards a 25W hydor at this point!

I agree with your points here. I have been challenged to find a heater that fits inside the side space nest to the filter in the Spec V. I also want one that puts out enough heat to keep my Betta comfortable. I will keep an eye on the replies your receive in this thread.

Yep, its definitely a struggle! I actually read through your thread before making this post and was going to message you if I found a good one! Hopefully this can help us both

I have 5 Fluval canisters, (206, 2x 306, 406 and FX4) as well as Plant 2.0 48" and 3.0 36" lights. I love Fluval but their heaters are way overpriced for what they are. For adjustable heaters, the Aqueon Pro is possibly the best you can buy regardless of price. I've been testing a few different heaters and the HT10 is a great, inexpensive choice if you're ok with a preset heater. I bought 4 in the last year for QT, brine shrimp hatching, warming up RO water for my shrimp tank and other temporary needs. It fit perfect in the Spec III so it's been in there for over a year w/o issue. I haven't modded the Spec III and it keeps a steady 78°F in the tank.

I've tested Cobalt and Finnex heaters and they're good but too bulky. I have about 10 Aqueon Pros and a few regular Aqueon heaters. The regular aren't that great but the Pros are flawless. The newer models (LED on control knob) aren't as good as the older one but still pretty good.

Thank you so much for your response! I honestly have to agree, I'm specifically not going for the Fluval heater just because they are so overpriced. I've also heard very mixed reviews about how well they actually fit in the compartment, but I guess it just depends on who you ask! The Aqueon pro sounds amazing from what you described. Do you have a Spec V as well or just the III? And have you ever tried another heater with your tank? I would love to know your thoughts! Thanks!

 

Thanks for your response! Honestly a lot of these responses are making me more confused than ever I've heard from almost all Fluval Spec V owners that the best possible way to heat the tank without placing the heater in the main display is to puncture small holes in the pipe. For example, a lot of the information about this tank I have received from this website which is completely dedicated to spec tanks, I'll include the link here: Fluval Spec Flow Tube Modification With your experience with the Fluval Spec, do you recommend not making any modifications? Definitely going to add a baffle for the filter though!
I've also seen so many different aquarium companies recommending different wattages for different gallons. The general consensus seems to be 50W for the Spec V however reading your comments I think you might be right.. always better to be safe than sorry! Would you recommend just a 25W for keeping a Betta in 5 gallons? I live in Melbourne Australia, not sure if that helps give everyone an idea of the weather



Wow that's so interesting! So you don't use a baffle at all for your Betta and he can swim okay? The one I purchased is actually the newer Fluval, so hopefully it will be okay. However I am ready to reduce the outflow if need be! Thanks so much for your help, I'm actually leaning towards a 25W hydor at this point!



Yep, its definitely a struggle! I actually read through your thread before making this post and was going to message you if I found a good one! Hopefully this can help us both



Thank you so much for your response! I honestly have to agree, I'm specifically not going for the Fluval heater just because they are so overpriced. I've also heard very mixed reviews about how well they actually fit in the compartment, but I guess it just depends on who you ask! The Aqueon pro sounds amazing from what you described. Do you have a Spec V as well or just the III? And have you ever tried another heater with your tank? I would love to know your thoughts! Thanks!

Well FrostMystique, I do believe this can help us both. If you have, or need, additional info, you can message me. I tried from my end .... no can do.

 

Thanks for your response! Honestly a lot of these responses are making me more confused than ever I've heard from almost all Fluval Spec V owners that the best possible way to heat the tank without placing the heater in the main display is to puncture small holes in the pipe. For example, a lot of the information about this tank I have received from this website which is completely dedicated to spec tanks, I'll include the link here: Fluval Spec Flow Tube Modification With your experience with the Fluval Spec, do you recommend not making any modifications? Definitely going to add a baffle for the filter though!
I've also seen so many different aquarium companies recommending different wattages for different gallons. The general consensus seems to be 50W for the Spec V however reading your comments I think you might be right.. always better to be safe than sorry! Would you recommend just a 25W for keeping a Betta in 5 gallons? I live in Melbourne Australia, not sure if that helps give everyone an idea of the weather

DarkOne isn't wrong about the price being high. I bought that Fluval because I knew it would fit, but I also just bought the Aqueon Pro for another betta tank I have set up at my office, and it would definitely fit as well. Also, five years later my Fluval heater still works, and the glass sleeved 50W Tetra heater I got with my new betta tank (from my sister) did just as I have noted...failed "on" and took the tank to about 86 degrees.
Ultimately it's your choice. I feel the Fluval is worth the price, as most things in this hobby tend to be.

I read the article on the flow tube modification. I thought you were talking about drilling holes in the compartment wall between the return section and the display. However, I stand with my original opinion that no modifications are needed other than an output baffle, and even that is a matter of choice - my betta has stupid long fins and he was helpless against the flow. I choose to run my filter at full speed to keep water moving through the media. Now, back to the tube drilling... If you drill holes in that tube, the pump is going to push water out of the holes, right? So you get nice circulation around your heater, but again the system is designed so that the pump pumps water out of the sump area, thereby causing it to be pulled in through the overflow slots. SO if your pump is pumping water back into the pump chamber, that reduces the whole system wouldn't it?

...But I have my doubts about most "mods". I figure, Fluval has spent a lot of money and probably paid a few engineers, designers, and scientists to design a system that balances form and function. So to me, the thought that some flat-brim-cap-wearing twenty-year-old whose most original greeting is "Yo 'Sup yall" is probably not going to actually improve on the design. But that's just me being old and uncool.

 

I originally got the Marina 50w and it did fit in the filter compartment but my house got down to 60f in the winter and it wouldn't heat past 76f. I used the Aquatop 50w and it worked flawlessly.

 

DarkOne isn't wrong about the price being high. I bought that Fluval because I knew it would fit, but I also just bought the Aqueon Pro for another betta tank I have set up at my office, and it would definitely fit as well. Also, five years later my Fluval heater still works, and the glass sleeved 50W Tetra heater I got with my new betta tank (from my sister) did just as I have noted...failed "on" and took the tank to about 86 degrees.
Ultimately it's your choice. I feel the Fluval is worth the price, as most things in this hobby tend to be.

I read the article on the flow tube modification. I thought you were talking about drilling holes in the compartment wall between the return section and the display. However, I stand with my original opinion that no modifications are needed other than an output baffle, and even that is a matter of choice - my betta has stupid long fins and he was helpless against the flow. I choose to run my filter at full speed to keep water moving through the media. Now, back to the tube drilling... If you drill holes in that tube, the pump is going to push water out of the holes, right? So you get nice circulation around your heater, but again the system is designed so that the pump pumps water out of the sump area, thereby causing it to be pulled in through the overflow slots. SO if your pump is pumping water back into the pump chamber, that reduces the whole system wouldn't it?

...But I have my doubts about most "mods". I figure, Fluval has spent a lot of money and probably paid a few engineers, designers, and scientists to design a system that balances form and function. So to me, the thought that some flat-brim-cap-wearing twenty-year-old whose most original greeting is "Yo 'Sup yall" is probably not going to actually improve on the design. But that's just me being old and uncool.

You're right - if I know it works for sure I will definitely be investing in a better quality heater. The problem is still which one, with the main issue being different people having different problems with different ones! If it comes down to it though, I may just settle for a more expensive one such as the Fluval!
The drilling holes modification would reduce the overall performance of the filter, which was something I was originally fine with. However reading your post has made me think maybe that is not such a good idea - I was originally going to do this because it reduced the outflow for my Betta, but if I decide to re-use this tank for other fish that might not work as well. So once again you are right!

 

Well FrostMystique, I do believe this can help us both. If you have, or need, additional info, you can message me. I tried from my end .... no can do.

Thanks!

 

I’ve just been in the local pet store which is having a closing down sale (hooray! No more Betta’s in tiny tanks and employees giving bad advice!) and I saw quite a large piece of wool being sold for $1. I was just wondering whether anyone had any ideas about some how making this into a baffle for the nozzle? I have seen people making wool into a baffle for Bettas in the past but I would love some ideas! I’ve attached a photo thanks in advance!