TL;DR: The Shark Clean & Empty Cordless Stick Vacuum BU3521 is a lightweight, 15-bar powerful cleaning solution featuring a game-changing 1.3L auto-empty dock. Perfect for pet owners and allergy sufferers, it traps 99.97% of dust and allergens while offering up to 40 minutes of runtime for effortless, hands-free home maintenance.
Shark Clean & Empty BU3521 Key Features
- Primary Keyword: Shark Clean & Empty Cordless Stick Vacuum BU3521
- Auto-Empty System: Hands-free 1.3L base holds up to 30 days of debris.
- HEPA Filtration: Anti-Allergen Complete Seal captures 99.97% of particles.
- Weight: Redesigned chassis is 30% lighter than the Shark Vertex Pro.
- Runtime: Up to 40 minutes of cleaning in ECO mode.
- Brushroll: Self-cleaning PowerFins technology prevents hair wrap.
- Versatility: Converts to a handheld vacuum for stairs and upholstery.
- Display: LED interface monitors battery and suction modes in real-time.
The Real Talk Review
If you hate touching dust, the Shark Clean & Empty Cordless Stick Vacuum BU3521 feels like a miracle. It’s incredibly light, making it the best choice for carrying up and down stairs without the usual backache. The suction is punchy enough for daily pet hair, and the auto-empty base is addictive—you simply dock it and walk away.
The Catch: While the base holds a month of dirt, the small dust canister on the vacuum itself fills up fast. If you have a large, high-shedding dog, the vacuum might need to “visit” the dock mid-clean to stay efficient. Also, the 40-minute battery life is generous on hard floors but drops significantly if you use “Boost” mode on thick carpets.
Real User Opinions
“This vacuum is a lifesaver for my asthma. I used to sneeze every time I emptied my old vac, but this sealed system keeps the dust totally contained. Just wish the battery lasted 10 minutes longer!” — Lucille H.
“It’s so light it feels like a toy, but the suction is the real deal. It handles my three cats’ fur easily. My only gripe is that it can’t stand up on its own away from the dock.” — Megan S.
“The auto-empty feature is 10/10. However, it is quite noisy when it’s emptying into the base—kind of like a mini jet engine for about 15 seconds. Don’t do it while the baby is sleeping!” — James K.
People Also Ask
How often do I need to empty the Shark BU3521 base?
The 1.3L auto-empty base on the Shark Clean & Empty Cordless Stick Vacuum BU3521 is designed to hold up to 30 days of dust and debris. However, if you have multiple pets or high-traffic areas, you may find yourself emptying the large base every 2–3 weeks to maintain peak airflow.
Does the Shark Clean & Empty BU3521 work on thick carpets?
Yes, it features a self-cleaning brushroll that adjusts to different floor types. While it excels on hard floors and low-pile rugs, users with very thick or shag carpets should use the “Boost” mode for a deeper clean, though this will reduce the total battery runtime.
Is the filter in the Shark BU3521 washable?
The pre-motor foam and felt filters are washable and should be cleaned once a month. The HEPA filter in the base should be rinsed once a year. Always ensure filters are completely air-dried for at least 24 hours before reinserting them to prevent motor damage.
What attachments come with the BU3521 model?
The Shark Clean & Empty Cordless Stick Vacuum BU3521 typically includes a Duster Crevice Tool for tight spaces and a Pet Multi-Tool for upholstery. Note that the charging base only has an integrated storage spot for one of these tools, so you’ll need a place for the spare.