They are made for ponds. In the basket of an aquarium filter, a fine medium offers more surface area for the same volume.

Pile of black plastic bio balls with fins, biological media for a pond filter

EHEIM bioballs for pond filters

18,90 €

Quantity	Price	Price per unit	vs 55
55	18,90 €	0,34 €	—
110	33,90 €	0,31 €	−9 %

6,30 € × 3 with no fees Klarna.

These perforated EHEIM spheres made of pH-neutral plastic fill the biological stage of a pond filter. They provide surface area for bacteria without slowing the flow, and are rinsed in pond water before being put back in place. The pack contains 55 or 110 pieces.

Ref. H2518051·Bioballs

Quantity : 55

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The summary

What you receive: 55 pieces weighing 213 g, or 110 pieces weighing 426 g.
What they do: they house the bacteria without reducing the flow of water.
How to choose: loose spheres for a basket, a sheet for a made-to-measure housing.
What maintenance they need: a rinse in pond water when they are visibly clogged.

Perforated EHEIM spheres that fill the biological stage of a pond filter

A pond filter receives far larger volumes than an aquarium filter, it has to cope with leaves and sludge, and it must run for weeks without you opening it. Its biological stage therefore needs a medium that offers surface area to the bacteria without blocking the flow of water. These EHEIM bioballs, perforated spheres of black plastic, are the original biological media of LOOPpro pond filters, and they suit any biological chamber in a pond filter.

55 pieces, 213 grams

It is the top-up format, for completing an already well-stocked basket or equipping a small bedroom.

110 pieces, 426 grams

This is the format that fills the biological chamber of a typical pond filter.

💨 Surface area and water flow

The fins of a bioball multiply the surface area on which the bacteria attach, while the gaps between the spheres let the water circulate freely. This compromise suits a pond: a very fine mass would offer more surface area, but it would clog within a few weeks and the water would leave via the overflow untreated. The plastic is pH neutral, so the spheres change neither the pH nor the hardness of your water, either at start-up or after years of use.

🌊 Rinsing in pond water

These spheres do not need replacing. When they are visibly clogged with debris, rinse them in a bucket of pond water and put them back, because the chlorine in tap water would destroy the colony your filter took several weeks to establish. As with any biological media, do not rinse the whole volume on the same day: the part left in place reseeds the part you have rinsed. In spring, the load on a pond rises as feeding resumes while the colony is still coming out of winter, and the article on green pond water explains how to get through this period.

Pre-filtration comes before the spheres

A bioball lets particles through, since that is its design. If your water stays cloudy, the answer is mechanical and lies upstream of this chamber, in a brush, a grid or a sheet of foam. A biological chamber fed with water laden with sludge will in any case clog despite the gaps, because the mud ends up setting solid between the spheres.

A foam sheet upstream of the biological chamber

A cut-to-size filter foam sheet can be trimmed to the exact dimensions of your inlet chamber and stops particles before they reach the spheres. It suits a shop-bought filter just as well as a custom-built box. The bioballs then stay clean for longer, and you open the biological chamber less often.

🔄 Extending an existing filtration system

To increase the biological capacity of your filter when it is already running, add the new spheres alongside the existing media rather than replacing it. The bacteria in the old media colonise the new in a few weeks, and you only remove the old media later if space runs short. A storage net makes handling easier, since it lets you lift the loose media out in one go when rinsing. On a new pond or after a harsh winter, concentrated pond bacteria, dosed to the pond volume as soon as the water rises above 10 °C, speed up the establishment of the colony on the spheres.

🐟 The biological chamber in aquaponics

When the fish tank of an aquaponic system is an outdoor pond, the biological chamber of its filter supplies a large share of the nitrate that the crops take up: the fish's ammonia is oxidised there to nitrite, then to nitrate. The volume of biological media therefore limits the fish load your system can sustain, more than the growing surface does. The EHEIM LOOPpro pond filter holds these spheres in its dedicated chamber, and the guide to the nitrogen cycle in aquaponics explains each of these transformations in detail.

Technical specifications

The essentials

Material: pH-neutral plasticIt does not alter any water parameter.
Shape: Perforated sphere with slatsThe lamellae provide the surface, the gaps provide the flow.

Use

Purpose: Biological pond filter chamberAfter the pre-filtration, never in direct contact with the raw water.
Maintenance: Rinsing in pond waterOnly when they are visibly clogged.

Pack sizes

55-piece pack: 213 gTo round off an order or equip a small bedroom.
110-piece pack: 426 gThe size that fits a typical biological chamber.

To budget for separately

Pre-filtration: A foam sheet to cut to sizeThe particles are stopped before the biological chamber.
Net or basket: To lift the loose media out in one goIt saves you picking up the spheres one by one when rinsing.

In the box

55 or 110 loose bioballs, depending on the size chosen

Sizes, material and use taken from the manufacturer's data on 11/10/2026; weights per pack taken on 20/09/2026.

Loose spheres or foam sheet?

Two ways of filling the same filter chamber, which do not trap the same things.

Two ways of filling the same volume The spheres let water through and do not clog. The sheet stops what passes through and can be cut to size.

	Form supplied	Material	Traps particles	Houses the bacteria	Fits a custom-made chamber	Lets water through without clogging	Pieces per pack (pieces)	What the set contains	Price
Recommended EHEIM bioballs for pond filtersYour choice	Loose spheres	pH-neutral plastic	No	Yes	No	Yes	110 pieces	55 or 110 spheres	18,90 €
Filter foam sheet to cut to size, 1.2 m²Your choice	Cutting plate	Open-structure synthetic media	Yes	Yes	Yes	No	1 pieces	1.2 m² in a single sheet	74,90 €

EHEIM bioballs for pond filtersRecommended

What it is

Form suppliedLoose spheres

MaterialpH-neutral plastic

What the mass does

Traps particlesNo

Houses the bacteriaYes

Fits a custom-made chamberNo

Lets water through without cloggingYes

Format

Pieces per pack (pieces)110 pieces

What the set contains55 or 110 spheres

Filter foam sheet to cut to size, 1.2 m²

What it is

Form suppliedCutting plate

MaterialOpen-structure synthetic media

What the mass does

Traps particlesYes

Houses the bacteriaYes

Fits a custom-made chamberYes

Lets water through without cloggingNo

Format

Pieces per pack (pieces)1 pieces

What the set contains1.2 m² in a single sheet

Manufacturer's values and packaging measurements recorded on 11/10/2026.

Estimate your
delivery time

Lightweight parcel, dispatched within 48 hours by Colissimo or Chronopost to your home, as you choose at payment. The exact cost depends on the method selected.

Frequently asked questions

8 questions

6 key questions, 8 in the detailed view

Aquarium or pond?

How many pieces for my filter?

Do they need rinsing under the tap?

Do they need replacing regularly?

Does it clear the water?

Do they change the pH or the hardness?

How do you add them to another biological medium?

Are they useful on an aquaponic circuit?

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EHEIM bioballs for pond filters

The summary