AIO Experiences

RossB · May 14, 2026

Looking at purchasing an IM AIO Fusion 40L. I will be doing a mixed reef setup I think as I have limited experience with corals so want to start slowly. Before I go to far down the planning phase, looking to get some feedback on the following:
- How quiet are IM AIOs?
- How close to the wall can they be? Manual recommends 5-6 inches away, but I don't have that much space. I am probably looking at about 3-4 inches.
- Recommendations on lights for tank?
- I plan on using an N-Clear M Fleece Roller Filter instead of sock and want to put a refugium in one of the reactor chambers? Should I put it on the same side as fleece roller or on the opposite side? I will probably use the IM 9W refugium light that they sell.
- Is it okay to install heater and the ATO stuff in the center return pump chamber? I know that putting heater in return sections of a sump is not recommended but not sure if that applies to AIO.

Appreciate any other advice or experiences shared.

exnisstech · May 14, 2026

My IM20 is near my bed. It's my first AIO and I love the simplicity of it. You really only need room behind it for cords. I like enough room I can get my arm behind the tank. I upgraded the dual return pumps to a single jebao DC pump and it's silent. My heater is in the return chamber. I use an inkbird controller that has two sensors and I have one in the display and the other in an overflow section. Its been fine this way for over a year. They can make gear choices difficult because of the lack of space. I run mine simple with no skimmer or mechanical filtration other than some floss when I'm blowing rocks or scraping glass.

JumboShrimp · May 14, 2026

I'm with @exnisstech, it's a good tank. Personally, you don't 'need' more than 3-4 inches behind the tank for it to function... but I like to get my arm 'more back there' if I ever needed to (spill?), and to keep salt creep further from a wall. But 3-4 inches is doable.

Fish Fan · May 14, 2026

I have several IM AIO's from 10 to 25 gallons, and I very much like them. I know other members here that have larger IM AIO's they are happy too. IM makes a well liked product, I think you'll be happy with it.

My IM 25 build has the tank basically backed right up to a wall. That makes adding things like protein skimmers a bit more challenging, but it's not a huge issue. I believe if you left 2 or 3 inches between the back of the tank and your wall, you'd be just fine. 5 inches or so is way too far from the wall, no one does that

Good luck!

DavidA · May 14, 2026

RossB said:
Looking at purchasing an IM AIO Fusion 40L. I will be doing a mixed reef setup I think as I have limited experience with corals so want to start slowly. Before I go to far down the planning phase, looking to get some feedback on the following:
- How quiet are IM AIOs?
- How close to the wall can they be? Manual recommends 5-6 inches away, but I don't have that much space. I am probably looking at about 3-4 inches.
- Recommendations on lights for tank?
- I plan on using an N-Clear M Fleece Roller Filter instead of sock and want to put a refugium in one of the reactor chambers? Should I put it on the same side as fleece roller or on the opposite side? I will probably use the IM 9W refugium light that they sell.
- Is it okay to install heater and the ATO stuff in the center return pump chamber? I know that putting heater in return sections of a sump is not recommended but not sure if that applies to AIO.

Appreciate any other advice or experiences shared.

I love my IM 40L AIO. It is very quiet. I like loads of room behind it but it should function with 3-4 inches though maintenance of cords and dosing tubes will be more difficult. I run a heater, ATO sensors, probes and dosing tube into the return reservoir. I use a 2nd compartment for a chaeto refugium lit by the IM chaetomax light. I like the light. . I started with an IM roller adjacent to the refugium but found that I could not service the refugium without removing the roller. I initially moved the roller to the opposite side and now have removed all mechanical filtration (except IM aqua gadget protein skimmer) to maximize pods for my mandarin. The protein skimmer is decent. I also use the IM media reactor for GFO. It is adequate but the flow rate frequently changes. I use 2 16D AI lights at about 55%.

overhead · May 14, 2026

I have a 15 gallon IM AIO. Assume it is similar, but it is quiet. Had a little waterfall type noise but that could be adjusted by raising the water level in the pump chamber. Pump and skimmer are DC, so it is pretty much silent.

dvgyfresh · May 14, 2026

I love the AIO , only isssue I’ve had is fighting algae lol but I think that’s always a problem

exnisstech · May 14, 2026

RossB said:
Is it okay to install heater and the ATO stuff in the center return pump chamber? I know that putting heater in return sections of a sump is not recommended but not sure if that applies to AIO

I had forgotten about this post showing the back chamber layout if an IM20. If a 40 is the same design down at the bottom as shown is where I'm moving mine too the next time I'm working back there.