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Canister filter buying guide: match the stated litres

Updated: 23 October 2026

You are moving a community tank of 50–330 litres off an internal filter, and the next listing leads with a litres-per-hour figure that looks like a tank size. This canister filter buying guide puts the maker’s stated range first, then tells you which flow number you are reading. Shelf prices and ratings are amazon.co.uk figures from 20 October 2026, with no lab tank run. A qualifying purchase from the main [canister filter comparison](/hub/diy-supplies/canister-filter) can earn a commission at no extra cost to you. After the band is clear, [best canister filter](/hub/diy-supplies/canister-filter/sub/canister-filter-best) names one pick, [Fluval 207 or 307](/hub/diy-supplies/canister-filter/sub/canister-filter-fluval-207-or-307) splits those two models, and [how to set up a canister filter](/hub/diy-supplies/canister-filter/sub/canister-filter-how-to-set-up) is the first start.

You are moving a community tank of 50–330 litres off an internal filter, and the next listing leads with a litres-per-hour figure that looks like a tank size.

Our top picks

Fluval Fluval 207 external filter

Best overall

Fluval Fluval 207 external filter
9.2/10about £124.99
View offer
Fluval Fluval 307 external filter

Alternative

Fluval Fluval 307 external filter
9.0/10about £159.99
View offer
Oase Oase FiltoSmart 60

Best value

Oase Oase FiltoSmart 60
7.8/10about £43.56
View offer
On this page
  1. 1.Start with the maker’s tank range, not the flow title
  2. 2.Read pump output and filter circulation as two numbers
  3. 3.Treat other brands’ single flow figure with the rating method
  4. 4.Check power, plug, and what the filter will not do

Start with the maker’s tank range, not the flow title

Fluval’s UK 07 series page is the range you can hold against the litres you already know. The 107 is stated for 40–130 litres, the 207 for 60–220 litres, and the 307 for 90–330 litres. Oase’s FiltoSmart 60 page stops at 60 litres. A 50 litre tank sits with the 107 or the Oase, a 120 litre community tank sits inside the 207, and a tank past 220 litres is the 307’s ceiling in this set. The amazon.co.uk bullets do not print those litre bands. On 20 October 2026 the 107 was £109.99, the 207 £124.99, and the 307 £159.99. A 1,200 L/h title is a pump sentence. From 90 to 220 litres both the 207 and the 307 apply.

Read pump output and filter circulation as two numbers

Fluval prints two flow figures, and the smaller one is the one to put next to the tank. On the 107 the pump is 550 L/h and circulation is 360 L/h. On the 207 the pump is 780 L/h and circulation is 460 L/h. On the 307 the pump is 1,150 L/h and circulation is 780 L/h. The circulation number is the lower figure Fluval publishes for water going through the media. Four to six times the tank volume an hour is a UK hobby rule of thumb, and it can sit above Fluval’s circulation figure while Fluval still rates the 207 to 220 litres. No British Standard in these sources sets a legal turnover. Oase states a single 300 L/h for tanks up to 60 litres at 5 W. The watts are 10 W for the 107 and the 207, and 15 W for the 307 on Fluval’s 230–240 V line.
Fluval Fluval 207 external filter

Testsieger

Fluval Fluval 207 external filter
9.2/10about £124.99
View offer

Treat other brands’ single flow figure with the rating method

AQQA, Hidom, and the two unbranded canisters each print one litres-per-hour number. The AQQA AQ150 was £62.29, 4.1 from 47 ratings, 18 W, 1,200 L/h, stated up to 250 litres. UK reviews say branded sponges were not sold, and one buyer cut shop sponge to fit. The Hidom EX-1200 was £64.94, 4.1 from 100 ratings, 28 W, 1,200 L/h, and a recommended tank up to 600 litres. Fluval’s 307, at a similar pump figure of 1,150 L/h, is rated to 330 litres, so that 600 litre line is a different method. Both grey canisters print FK121 on different listings: 20 W and 1,400 L/h at £89.99 from 5 ratings, and 30 W and 1,800 L/h at £99.99 from 10 ratings.

Check power, plug, and what the filter will not do

UK mains are 230 V, and a domestic flex has to suit a BS 1363 socket. The Electrical Equipment (Safety) Regulations 2016 cover safe design, English instructions, and UKCA or CE marking for Great Britain. Regulation 35 of SI 2016/1101 is the plug rule for England, Wales, and Scotland. These listings do not prove a UK three-pin plug in the photograph. The 207 listing prints 240 V. The 307 listing row prints 220 V, while Fluval’s series page prints 230–240 V, and both figures stay as printed. Oase states 230 V at 50 Hz. If a Schuko plug arrives, use the right lead or a return. Filing the pins to fit a UK socket is outside these sources. Oase states self-venting, the 207 bullets name AquaStop valves, and a dry impeller is a fault.

Common questions

What size canister filter do I need for my tank in litres?
Match the litres you keep to a range the maker prints. In this set that is Fluval 107 at 40–130 litres, Fluval 207 at 60–220 litres, Fluval 307 at 90–330 litres, or Oase FiltoSmart 60 up to 60 litres. A 1,200 L/h title is a flow claim. Hidom’s up to 600 litres is Hidom’s own line, and Fluval rates a similar pump figure only to 330 litres.
Is the litres-per-hour number on the box the flow I will actually get?
On Fluval, the pump output is the higher number and the filter circulation is the lower one: 780 L/h and 460 L/h on the 207, for example. The circulation figure is the one Fluval publishes for water through the media. AQQA, Hidom, and the two FK121 listings print a single litres-per-hour figure, so you only have that one claim. Head height, hose length, and a clogged pre-filter all change what you see in the tank.
Is four to six times the tank volume per hour a legal requirement in the UK?
No statute in these sources sets a turnover rate for a home aquarium. Four to six times the tank volume per hour is a UK hobby rule of thumb, and some shops publish higher multiples for messy tanks. Fluval can still rate a 200 litre tank inside the 207’s 220 litre ceiling while the 207’s circulation sits at 460 L/h, which is below four times 200. Use the maker’s litre band as the rating, and treat the multiple as a hobby check.
What should I check on the plug before I buy?
UK mains are 230 V. Regulation 35 of SI 2016/1101 requires a correct BS 1363 plug for domestic equipment in England, Wales, and Scotland. These listings do not prove that plug from the photo, so check it when the parcel arrives. The 207 page prints 240 V. The 307 page prints 220 V, while Fluval’s series page prints 230–240 V.
Does a bigger flow number mean I can skip water changes?
A larger pump figure is a flow claim, and it leaves the weekly test in place. OATA’s freshwater sheet says ammonia and nitrite should read zero once fish are in, and that you test at least weekly. These sources do not show a canister clearing nitrate well enough to drop water changes. Fluval’s manual also says you should never replace all the media at once, because the bacteria live in what you would throw away.

Related pages

Canister filter leaking

Canister filter

Best canister filter when the tank is 60–220 litres

Fluval 207 or 307 when the ranges overlap at 200 L

How to set up a canister filter without a dry start

Sources

Public UK sources and the amazon.co.uk listings compared on this page. Updated 22 October 2026.

  1. Fluval 07 series, UK (retrieved 22 October 2026)
  2. Fluval 07 manual (retrieved 22 October 2026)
  3. Oase FiltoSmart 60, en-GB (retrieved 22 October 2026)
  4. GOV.UK: Electrical Equipment (Safety) Regulations 2016 (retrieved 22 October 2026)
  5. legislation.gov.uk: SI 2016/1101 regulation 35 (retrieved 22 October 2026)
  6. OATA: how to test freshwater aquarium water (retrieved 22 October 2026)
  7. OATA water quality criteria, October 2022 (retrieved 22 October 2026)
  8. Maidenhead Aquatics: Fluval 07 (retrieved 22 October 2026)