How to Choose an Internal Aquarium Filter: 300, 450 or 450 Corner
By AllPetSolutions | Published: 2026-10-31
Category: Buying Guides
Match your tank volume to the right flow rate and shape: a 300L/H filter for tanks up to 70 litres, or a 450L/H unit for up to 90 litres, with a corner version to save front-pane space.
Quick answer
Choose the 300L/H internal filter for tanks up to 70 litres, the 450L/H standard internal filter for tanks up to 90 litres when you want built-in chemical filtration, or the 450L/H corner filter for tanks up to 90 litres where keeping the front and side panes clear matters more than an internal carbon tray.
Flow rate: why 300L/H and 450L/H suit different tank sizes
Flow rate is the first filter spec to match to your tank, because too little turnover leaves waste circulating and too much current can stress fish or disturb substrate and plants. The 300L/H model is rated for tanks up to 70 litres, while both 450L/H models are rated for tanks up to 90 litres. That step up in flow is the main reason to choose a 450 over the 300, not extra media capacity.
In a planted tank, strong flow can bend stems and push CO2 or nutrients past the leaves too quickly. If you are set on a 450L/H unit for a smaller or heavily planted tank, use the adjustable spray bar to direct output along the surface rather than straight down into the plants.
Shape and placement: corner vs standard internal filter
A corner internal filter is shaped to sit in the back corner, which keeps the front and side panes clear for viewing and gives plants and hardscape more usable space. That matters most as the tank gets bigger and the equipment gets larger with it. A standard internal filter typically mounts on a flat back or side pane and may be easier to reach for maintenance depending on your cabinet and lid layout.
The trade-off is filtration features, not flow: the 450L/H corner model does not list an internal carbon tray, while the standard 450L/H model does. If your water discolours or smells even with clean sponge, the standard 450IF gives you a chemical stage without adding an external filter.
Aeration options and power use
All three filters are submersible-only and include an adjustable spray bar to raise oxygen levels at the surface. The 300L/H and standard 450L/H models also include a venturi aeration nozzle as an alternative, which creates bubbles and increases oxygen exchange. The 300L/H model draws only 2W, which is worth noting for small tanks where you want low running cost and minimal heat added to the water.
If your tank already has an air pump or a separate aeration source, the spray bar alone is usually enough. The venturi option is more useful in a tank with little surface movement and no other air source.
Decision rules for choosing your internal filter
- Tank volume up to 70 litres: Choose the 300L/H internal filter. It is rated for that range and its 2W draw keeps running costs and heat low in a small tank. If your tank is closer to 70 litres and heavily stocked, check that the spray bar can be aimed to avoid dead spots before assuming 300L/H is enough.
- Tank volume 70–90 litres, standard back-pane placement: Choose the 450L/H standard internal filter. You get the higher flow plus an activated carbon tray for chemical filtration, and the venturi nozzle gives you an aeration alternative to the spray bar.
- Tank volume 70–90 litres, clear front and side panes wanted: Choose the 450L/H corner filter. It tucks into a corner and keeps the viewing panes clear, but it does not list an internal carbon tray, so plan chemical filtration separately if you need it. Measure your corner space and lid cutouts first; a corner shape only helps if it fits without blocking the filter intake.
- Planted tank with delicate stems: Prefer the 300L/H model for tanks up to 70 litres, or the 450L/H models with the spray bar aimed along the surface. Strong direct flow can bend plants and push nutrients past the leaves.
- Water discolours or smells despite clean sponge: Choose the standard 450L/H model, which includes an activated carbon tray. The 300L/H and corner 450L/H models do not list a chemical stage, so you would need to address discolouration another way.
Product facts
- AllPondSolutions 300L/H Aquarium Internal Filter 300IF: Rated for tanks up to 70 litres and draws 2W, with an adjustable spray bar and a venturi aeration nozzle included. This is the lowest-flow, lowest-power option, so it suits small tanks where a 450L/H current would be too strong.
AllPondSolutions 300L/H Aquarium Internal Filter 300IF - AllPondSolutions 450L/H Aquarium Internal Filter 450IF: Rated for tanks up to 90 litres and includes an activated carbon tray inside the unit alongside its sponge. The carbon tray gives you a chemical filtration stage for discoloured or odorous water without buying a separate filter.
AllPondSolutions 450L/H Aquarium Internal Filter 450IF - AllPondSolutions 450L/H Aquarium Internal Corner Filter 450-CIF: Corner-shaped and rated for tanks up to 90 litres, with an adjustable spray bar and submersible-only use. It keeps the front and side panes clear, which is the main reason to choose it over the standard 450L/H model.
Who these filters suit
Best for
- Fresh or salt water tanks up to 90 litres where you want a submersible internal filter with an adjustable spray bar
- Small tanks up to 70 litres that need low power draw and gentle flow
- Aquarists who want built-in chemical filtration without an external filter (standard 450L/H model)
Not for
- Tanks larger than 90 litres, which need a higher-flow or external filter
- Setups that require a filter to run outside the water, since all three models are submersible-only
- Anyone who needs a built-in carbon tray and a corner shape in the same unit, as no single model here lists both
