Fluval 06 series Primer Assembly with Primer Cover
Water type
Freshwater + Marine
Fits
Fluval 106, Fluval 206, Fluval 306, Fluval 406
Part no.
A20021
Fluval 06 series Primer Assembly with Primer Cover
Restores one-touch priming to an 06 Series canister that will not draw water. The Fluval self-primer is the pump handle and cover on the filter head that pulls the first water through the hoses, so the canister fills itself instead of being siphon-started by hand. When the diaphragm perishes, the filter will not restart after a clean. This is genuine Hagen part A20021, supplied with its primer cover, and Fluval lists it for the 106, 206, 306 and 406 only.
Key features
- Genuine Fluval A20021 — the number in Fluval's own 06 Series parts list
- Primer cover included — a cracked cover is replaced at the same time
- No siphon starting — a few strokes draw water in and air leaves through the output nozzle
- Fitted from the top of the head — no need to open the canister or disturb the media baskets
Specifications
| Manufacturer part number | A20021 |
|---|---|
| Part name | Self-primer assembly with primer cover |
| Fits | Fluval 106, 206, 306, 406 |
| Does not fit | 04 and 05 Series (these use A20020), 07 Series, FX Series |
| Suits | Freshwater and marine |
Will it fit my filter?
Only the 06 Series. The model number is on the canister body and under the motor head.
| Model | Aquarium capacity | Pump output | Circulation with media | Max. head |
|---|---|---|---|---|
| Fluval 106 | 100 L | 550 L/h | 360 L/h | 1.45 m |
| Fluval 206 | 200 L | 780 L/h | 460 L/h | 1.45 m |
| Fluval 306 | 300 L | 1,150 L/h | 780 L/h | 1.75 m |
| Fluval 406 | 400 L | 1,450 L/h | 930 L/h | 2.25 m |
Pump output is measured with an empty canister at zero lift. Circulation with media loaded is what the tank actually sees — on a 406, 930 L/h rather than 1,450 L/h. Both figures are from Fluval's 06 Series manual.
Suitable for, and not suitable for
- Suits a filter that runs once started but will not prime itself after a service
- Suits a handle that feels slack, will not spring back, or draws no suction
- Not for 04, 05, 07 or FX Series canisters
- Not the fix for a filter that primes then runs weakly — that is usually the impeller or ceramic shaft
What's included
- One self-primer assembly and one primer cover
Hosing, the AquaStop valve and the head O-ring are separate parts.
Goes well with
- Ceramic impeller shaft and bushing (A20039) — the other common cause of a rough restart
- Aquarium rim connector (A20026) — holds hosing steady at the tank rim
- Hose-lock nuts (A20059) — for collars that weep after a service
Warranty and delivery
Supplied as a genuine Fluval service part. Any manufacturer's warranty applies in addition to your rights under the Australian Consumer Law, which are not limited by it. Ships as a standard small parcel.
Common questions
Which Fluval filters does the A20021 primer assembly fit?
The Fluval A20021 self-primer assembly fits the Fluval 106, 206, 306 and 406 canister filters. It does not fit the 04 or 05 Series, which use A20020, and it does not fit the 07 Series.
Does the A20021 include the primer cover?
Yes. The Fluval A20021 is supplied as the self-primer assembly together with its primer cover.
My Fluval 306 will not prime after cleaning — is the primer at fault?
Not always. Check that the AquaStop lever is pushed fully down, the motor head is seated and clamped, and the hoses are pushed right onto the barbs. Air drawn in at any of those points stops the primer building suction.
How is an 06 Series filter primed correctly?
Open the AquaStop fully, then pump the handle up and down until you hear water being drawn in, and leave the handle down. Air is expelled through the output nozzle and the tank surface bubbles briefly as the canister fills.
