Gravel cleaner bell, 21 to 48 cm

¥1,500

Model	Price	Price per m	vs 21 cm
21 cm	¥1,500	¥7,143	—
30 cm	¥1,600	¥5,333	−25 %
48 cm	¥2,600	¥5,417	−24 %

¥500 × 3 with no fees Klarna.

This siphon bell cleans the tank substrate during a partial water change: sand and gravel fall back into the bell, while the sludge and waste are carried away with the water. It comes in three lengths, 21, 30 and 48 cm, to be chosen according to the water depth of your tank.

Ref. A8002500·Aquarium maintenance

Model : 21 cm

21 cm

30 cm

48 cm

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The summary

What you receive: a siphon bell in 21, 30 or 48 cm, with its pipe, without motor or batteries.
What it does: it removes the sludge trapped between the grains while the heavier gravel settles back into place.
When to use it: during a partial water change, since the water removed is the water you were going to replace anyway.
Which length: the bell is chosen according to the water depth, not the volume of the tank.
Sand or gravel: both, provided you adjust the height at which you hold the bell.
Shipping: small tracked parcel, costs calculated at checkout.

Siphon bell that removes sludge from the gravel during a water change

The Amtra gravel cleaning bell removes sludge from the substrate of a tank during a partial water change: the heavier gravel drops back into the bell while the waste is carried away with the water. It comes in 21, 30 or 48 cm, to be chosen according to the water depth, and works by gravity, without electricity.

Between the grains of a tank's substrate, a fine, dark matter builds up, made of leftover food and waste. The bell removes it, because the water drawn up the tube carries the light particles away while the heavier gravel drops back into the bell. The water laden with sludge then leaves through the supplied pipe into a bucket.

🌀 How to do a water change

The bell is used during the partial water change, since that change removes a volume you are going to replace anyway: the siphoned water then carries away the sludge from the substrate instead of leaving clean. Prime the siphon with a few back-and-forth movements of the bell in the water, place it flat on the substrate, let the gravel swirl for a few seconds, then move on to the next area. On fine sand, hold the bell a little higher, so that the sand does not get drawn up the tube.

📏 Choosing the length

Choose the length according to the water depth of your tank, not its volume. Measure the distance between the floor and the surface, then take the bell that lets you work without plunging your wrist in. A bell that is too short forces you to wet your forearm on every pass, and one that is too long becomes difficult to manoeuvre in a narrow tank. All three models work by simple gravity, without electricity, and can therefore also be used on the fish tank of an aquaponic system, where organic matter builds up on the bottom.

21 cm

This model suits shallow tanks and hard-to-reach areas, where a tall bell gets in the way.

30 cm

This is the intermediate length, which suits the water depth of most living-room tanks.

48 cm

This model is designed for tall tanks and deep-water fish tanks that are worked from the edge.

The glove for the glass, the test for the timing

The bell removes the sludge settled on the substrate, but not the algae attached to the glass and the decor. For these surfaces, use the metal-fibre cleaning glove, which lifts the algae film during the same maintenance session. To find out whether your water change schedule is the right one, a nitrate test settles the question better than a hunch, since the nitrate level rises when water changes are spaced too far apart.

Siphon the substrate one section at a time

A substrate that is siphoned completely in a single session removes a good part of the bacterial population that processes nitrogen, and the nitrite level rises in the days that follow. So work in sections, tackling a different area each time, and leave several weeks between two passes over the same spot. Also avoid siphoning the substrate in the same week as a filter clean, as these two tasks affect the two main bacterial reserves in your system.

🧽 After the session

Looking after the tool itself comes down to rinsing it in clean water, pipe included, followed by thorough drying before storing it. A pipe left damp and rolled tightly develops an internal film that smells bad and ends up releasing particles on the next use. Store it unrolled or in a large loop rather than in a tight coil, since a sharp kink stays put and hampers priming. Finally, keep this bell for a single tank if you have several, or rinse it carefully between tanks, because a siphon is one of the most effective ways of carrying a disease from one aquarium to another.

Technical specifications

The essentials

Lengths: 21, 30 or 48 cmThe choice is based on water depth, not on volume.
Principle: Gravity siphoning

Use

The timing: During a partial water change
Treated soils: Gravel and sandOn fine sand, hold the bell a little higher.

How it works

Feed: None, no mains, no batteries
Consumable: None, it is rinsed in clean water

To budget for separately

Bucket: To receive the siphoned water
Glass cleaning: Metal-fibre glove

In the box

1 cleaning bell, 21, 30 or 48 cm depending on the length chosen
1 clear siphon pipe

Lengths, siphoning principle, priming and contents recorded on 19/09/2026 and 11/10/2026 from the AMTRA descriptions and packaging, codes 8023222019270, 8023222019287 and 8023222022645.

Manufacturer and product safety

Manufacturer: CAMON&CROCI Pet Group S.p.A.
Postal address: Corso Italia 22, 20122 Milano (MI), Italie (siège légal) ; site opérationnel : Via S. Alessandro 8, 21040 Castronno (VA), Italie
Contact: info@croci.net
Website: www.amtra.net

Information provided under Regulation (EU) 2023/988 on general product safety.

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delivery time

This bell goes out as a small parcel. The exact amount is calculated at checkout according to the total weight of your order and your destination.

Frequently asked questions

6 questions

6 key questions

Which length to choose?

Choose the length according to the water depth of your tank, measured from the floor to the surface, and not according to its volume.

Length	Suitable tank
21 cm	Shallow tank, nano aquarium, hard-to-reach corners
30 cm	Most living-room tanks
48 cm	Tall tank or deep fish tank worked on from the edge

A tube that is too short makes you plunge your arm in, while a tube that is too long gets in the way in a narrow tank.

Is the pipe supplied?

Does the gravel go out with the water?

Can it be used on sand?

Do you need to clean the whole floor every time?

Is it suitable for a fish tank in aquaponics?

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Gravel cleaner bell, 21 to 48 cm

The summary