# Marina i25 Internal Aquarium Filter

The Marina i25 Internal Aquarium Filter is a compact internal filter listed for aquariums up to 25 litres. Its claimed three-stage mechanical, biological and chemical filtration, plus a waterfall spout, suits buyers seeking a cartridge-based option for a small tank.

- [Original product page](https://bargainpostbox.co.uk/product/marina-i25-internal-aquarium-filter)
- [View offer](https://bargainpostbox.co.uk/visit/marina-i25-internal-aquarium-filter)
- Market: UK
- Language: en-GB
- Currency: GBP
- Brand: Marina
- Model: A131
- Category: Pet Supplies > Aquariums & Terrariums
- Price: 11.27 GBP
- Previous price: 13.99 GBP
- Discount: 19%
- Price checked: 2026-11-12T15:38:09.439Z
- Rating: 4.3 / 5
- Reviews: 1208

Prices and deal status are the latest recorded data, not a guarantee of availability. Confirm the price and availability with the store.

## At a glance

- Manufacturer claims three-stage mechanical, biological and chemical filtration.
- The replaceable power cartridge is described as easy to change.
- A waterfall spout is claimed to provide continuous oxygenation.
- Listed for aquariums up to 25 litres.

## Pros

- The stated 25-litre capacity makes its intended small-tank use clear.
- The three filtration types combine mechanical debris capture with biological and chemical filtration, according to the listing.
- A replaceable cartridge offers a straightforward maintenance approach.

## Specifications

### Identity
- Brand: Marina
### Dimensions and installation
- Dimensions listed: 7.62 x 8.13 x 20.32 cm; 300 g
- Size: i25
- Usage: Indoor
- Colour: Black
### Filtration and compatibility
- Listed tank capacity: 25 litres
- Filtration stages: 3 stage
- Filtration types: mechanical, biological, and chemical
- Style: Cartridge
### Product details
- Model number: A131
- Age range: All life stages
- Number of items: 1
- Batteries included: No

## Before you buy

- The 25-litre capacity and 6.6-gallon description are approximate equivalents. The listing also gives weight as both 0.4 Kilograms and 300 g, and calls the unit an internal filter while describing it as clip-on. Confirm the dimensions and installation style for your tank before buying. The manufacturer describes the filtration and oxygenation benefits, which are not independently verified here.

## In the box

- Marina i25 Internal Filter (Included)

## A good fit for

- Aquarium owners with a tank no larger than the listed 25-litre capacity.
- Buyers who prefer a compact internal filter with a replaceable cartridge and three stated filtration types.

## Less suited to

- Owners of aquariums exceeding the stated 25-litre capacity.
- Buyers who need a confirmed weight or a definitive clip-on versus internal installation description before purchase.

## Customer feedback

Customer feedback reports that buyers appreciate the filter's fit for small tanks, quiet operation, ease of cleaning and perceived filtration quality. Other feedback raises concerns about reliability and durability, including reports of units stopping after a day or breaking within a week, while views on whether pets are happy are mixed. For a small tank within the stated capacity, reported quiet running and easy cleaning may matter in day-to-day use, but the reliability reports make long-term performance less certain.
- Positive themes: Customers describe it as suitable for small tanks and report quiet operation.
- Positive themes: Customers praise ease of cleaning and perceived filter quality.
- Negative themes: Some customers report that the filter stopped working after one day or broke within the first week.
- Mixed feedback: Customer views on reliability, durability and pet happiness are mixed.

## Frequently asked questions

### What size aquarium is the Marina i25 listed for?
The manufacturer lists it for aquariums up to 25 litres, also described as 6.6 US gallons. Treat that as the stated limit rather than a guarantee of suitability for every tank setup.
### What kinds of filtration does it use?
The listing describes mechanical, biological and chemical filtration through three stages, using a power cartridge.
### Does the filter include a cartridge?
The manufacturer description says the power cartridge is included. Replacement cartridges are described as available, but the listing does not specify a replacement schedule.
### Is it installed inside the aquarium or clipped on?
The product is titled an internal filter, while the description calls it clip-on. The installation description is inconsistent, so check the selected listing and tank fit before purchase.

## Alternative options

- [Marina i160 Internal Filter](https://bargainpostbox.co.uk/visit/marina-i25-internal-aquarium-filter)
- [NICREW Magi Mini Fish Tank Filter, Internal Aquarium Filter for 20L Tank \| Surface Agitation, Oxygenation, Easy Setup & Maintenance, Filter Media Included, Extra Impeller Included, Fully Submerged](https://bargainpostbox.co.uk/visit/marina-i25-internal-aquarium-filter)
- [Quiet Fish Tank Filter 4in1 Internal Aquarium Filter for 20L-200L Aquarium \| for Freshwater and Saltwater,Water Clean,Water cycle,Submersible Water Pump,Oxygen Aeration,Wave Maker,Water Change,for pond](https://bargainpostbox.co.uk/visit/marina-i25-internal-aquarium-filter)
- [AQQA Fish Tank Filter, 750L/h Internal Aquarium Filter, 8W Quiet Fish Tank Filter Pump for Tanks up to 230L](https://bargainpostbox.co.uk/visit/marina-i25-internal-aquarium-filter)
- [IREENUO Adjustable Fish Tank Filter, 600L/H Internal Aquarium Filter Pump with Spray Bar, 6W Silent Submersible Filter for Small Tank Up to 120 Litres](https://bargainpostbox.co.uk/visit/marina-i25-internal-aquarium-filter)
- [AQQA Fish Tank Filter, Internal Aquarium Filter for Tanks up to 200L \| Ultra-quiet, 650L/h Adjustable Fish Tank Pump and Filter, Built-in Rainfall Aerator, Surface Agitation, Fully Submerged](https://bargainpostbox.co.uk/visit/marina-i25-internal-aquarium-filter)
- [hygger Fish Tank Filter, 4 in 1 Aquarium Filter Pump Internal, Fish Filter Pump, Turtle Tank Fliter, Filtration Circulation Oxygenation Wave-making, for 113-189L Freshwater Saltwater, 20W 800L/H](https://bargainpostbox.co.uk/visit/marina-i25-internal-aquarium-filter)
- [Aquapapa U-V Fish Tank Filter, Aquarium Filter with 6-Layer Filtration \| 8W 500L/H Fish Tank Filter Pump for 30–110L Tank, Sponge Filter with Aeration & Rainfall for Coldwater & Tropical Aquariums](https://bargainpostbox.co.uk/visit/marina-i25-internal-aquarium-filter)
- [ZaKaBox CF3 Replacement Filter for Interpet Internal Aquarium Filter \| 5+5 Pack\(10mm Thick Algaway Pads\) – 5 Month Service Kit for Coldwater & Tropical Fish Tanks](https://bargainpostbox.co.uk/visit/marina-i25-internal-aquarium-filter)
- [Mekturm 5 in 1 Internal Fish Tank Filter, Aquarium Filter Pump, UV Steriliser, Turns Green Water to Clear, Timing Flow Rate and Direction Adjustable, for 15-80L Aquarium](https://bargainpostbox.co.uk/visit/marina-i25-internal-aquarium-filter)
- [Cylindrical Internal Aquarium Fish Tank Filter 50~100 litres Tank,330L/H 5W \| Bottom Suction Design, 3-Stage Biochemical Sponge Filtration, Adjustable Water Flow/Air Flow, Easy Clean, Work in Freshwater](https://bargainpostbox.co.uk/visit/marina-i25-internal-aquarium-filter)
- [AQQA Fish Tank Filter, 500L/h Adjustable Aquarium Filter, 5W Quiet Fish Tank Filter Pump for Tanks up to 200L](https://bargainpostbox.co.uk/visit/marina-i25-internal-aquarium-filter)

## Add-ons

- [Marina i25 Filter Replacement Cartridge, Medium](https://bargainpostbox.co.uk/visit/marina-i25-internal-aquarium-filter)
- [Marina Decorative Aquarium Rainbow Gravel, Multi-Colour, 2 Kg](https://bargainpostbox.co.uk/visit/marina-i25-internal-aquarium-filter)

## Images

![Marina i25 Internal Aquarium Filter — 1](https://bargainpostbox.co.uk/i/ofyJWnR6g-gN7cZQ2pLxY2DsDDVG4Yqe-15zzjYdOcL8voJevIcv3RhtMdHy1qYZv0dl93g4ZN-d3tIIwPX3V_X3VeS8SrNU_PdsMDtv2ixNfsc5yhaLgMxw.jpg)

![Marina i25 Internal Aquarium Filter — 2](https://bargainpostbox.co.uk/i/7wZDdIg4hzSA8W0vTuqVvmCjbQ7I9nOyiGbCJsNiigqxdEiB_h-MfcCQEHOOb9HIsa6nzauE2g3nGU2Xsvu0Y59psK-gVYwjkWYMYUzOoSZfth7-iHKOAvOt.jpg)

![Marina i25 Internal Aquarium Filter — 3](https://bargainpostbox.co.uk/i/VbMdpfKQv7AoOS17gbse2enmJuaaj7QLXHzZacvykH-QGN9UhWMtVv-A11XTTEjJoJ7yABnLtRuKfoBtq1nAlfcvtaxNCSjj_VdJUj_Rpkpom8pfHasr8zbT.jpg)