← UNS 75A Dual AIO (Standard) · All nano protein skimmers
Best skimmers for the UNS 75A Dual AIO (Standard)
Choose a skimmer whose manufacturer-rated volume meets or exceeds your tank volume multiplied by a safety margin: 1.2× for light bioloads, 1.5× for medium, and 2.0× for heavy. This compensates for manufacturer overclaiming and the tendency to overstock nano tanks. If you're using an in-sump or in-chamber skimmer, confirm it physically fits the rear chamber, which is often only about 3 inches front-to-back; hang-on-back skimmers sidestep that constraint.
The UNS 75A is a Standard-size Dual All-In-One from Ultum Nature Systems, rated 40.1 gallons at 29.52 × 17.71 × 17.71 in in 8mm glass, with an integrated rear triple-chamber filter driven by a dual-pump setup. It ships without a light, and UNS publishes neither flow (GPH) nor rear-chamber internal dimensions, so size equipment by measurement. At 40 gallons it sits at the larger end of the AIO range.
AquaMaxx HOB-1 $189.99
- rated to 75g, covers your 60g medium-bioload target (tank + margin)
- hangs on back — no chamber-fit constraint
All skimmers compared
| Skimmer | Rated to | Mount | Price | Verdict |
| AquaMaxx HOB-1 AquaMaxx | 75 gal | HOB | $189.99 | Top pick |
| Classic 100-HOB Skimmer Reef Octopus | 105 gal | HOB | $334.94 | Recommended |
| Comline DOC Skimmer 9004 Tunze | 66.1 gal | in-chamber | $199.99 | Likely — verify fit |
| Classic 110-INT In-Sump Skimmer Reef Octopus | 130 gal | in-chamber | $326.85 | Likely — verify fit |
| Bubble Magus QQ1 Bubble Magus | 25 gal | HOB | $95.99 | Undersized |
| Comline DOC Skimmer 9001 Tunze | 37 gal | in-chamber | $149.99 | Undersized |
| K1-Nano Protein Skimmer IceCap | 30 gal | in-chamber | $98.16 | Undersized |
| Bubble Magus QQ2 Bubble Magus | 26 gal | in-chamber | $99.99 | Undersized |
| SkimMate Ghost Skimmer (Desktop) Innovative Marine | 20 gal | in-chamber | $149.99 | Undersized |
FAQ
Do I need a protein skimmer on a nano AIO?
It depends on your bioload. Lightly stocked tanks with frequent water changes can often skip a skimmer, but a heavily stocked nano benefits significantly from one. If you're running a heavy bioload, size up to a 2× safety margin on the manufacturer's rated volume.
Why apply a safety margin to the manufacturer's rated volume?
Skimmer manufacturers tend to rate their products under ideal, lightly stocked conditions. Nano tanks are also easy to overstock relative to their water volume. Multiplying the tank volume by 1.2 to 2.0 depending on bioload gives you a buffer against both factors.
My AIO rear chamber is only 3 inches deep — what are my options?
In-chamber skimmers must fit that footprint, and many don't. Measure the front-to-back and left-to-right dimensions of your chamber before buying. A hang-on-back skimmer avoids the fit problem entirely since it mounts on the tank's back wall instead of sitting inside the chamber.