Our verdict
Pick the Alen BreatheSmart 25i if you want the lower price. Pick the Alen BreatheSmart 35i if your room is larger.
The central trade-off
Rated room size. Alen BreatheSmart 35i: 1,400 sq ft; Alen BreatheSmart 25i: 800 sq ft.
Filters. Alen BreatheSmart 25i: HEPA.
Filters. Alen BreatheSmart 35i: HEPA.
Price. When we checked, the Alen BreatheSmart 25i listed for less ($179 against $289); prices move, so check both buttons.
Side by side
| Specification | Alen BreatheSmart 25i | Alen BreatheSmart 35i |
|---|---|---|
| Rated room size | 800 sq ft | 1,400 sq ft |
| Smoke CADR | Not stated by the maker | Not stated by the maker |
| CADR | Not stated by the maker | Not stated by the maker |
| Quietest setting | Not stated by the maker | Not stated by the maker |
| Noise | Not stated by the maker | Not stated by the maker |
| Power draw | Not stated by the maker | Not stated by the maker |
| Filters | HEPA | HEPA |
| Warranty | Not stated by the maker | Not stated by the maker |
Values are the makers' published specifications. "Not stated" means the maker doesn't publish it.