Aquarium Filter Size Guide: How to Match Tank Size, Flow & Filter Capacity
Choose an aquarium filter by manufacturer tank range, flow specification, livestock, media capacity and maintenance needs instead of relying on one universal turnover formula.
Aquarium filter sizing is often reduced to one multiplication rule: take the tank volume, multiply it by a target turnover number, and buy the nearest GPH or LPH rating. That math is useful for describing water movement, but it is not a complete sizing method.
Current manufacturer specifications show why. A filter can have a published aquarium-capacity range, a pump-output figure, a separate circulation figure, a media-volume specification and adjustable flow — all describing different parts of the system. Two filters with similar GPH numbers can also hold very different amounts of media or return water to the aquarium in very different ways.
The safer method is to use the manufacturer’s aquarium range as the first boundary, then check the exact flow specification, livestock, bioload, media capacity, tank layout and maintenance needs before deciding whether the smaller or larger model is the better fit.
Before applying the steps below, the aquarium filter sizing & flow calculator can compare your tank volume with an exact manufacturer range and calculate a label-preserving flow-to-volume ratio without turning that ratio into a universal target.
For tank-size buyer intent, use the 5-gallon filter guide for nano footprint and gentle-flow choices, the 10-gallon filter guide for small-tank architecture choices, the 20-gallon filter guide for compact HOB/canister/sponge options, the 29/30-gallon filter guide for exact-ceiling versus modest-headroom decisions, the 40-gallon filter guide for AC50/AC70 and 207/307 overlaps, the 55-gallon filter guide for the HOB-versus-canister crossover, the 75-gallon filter guide for higher-capacity HOB/canister choices, the 90-gallon filter guide for exact-capacity versus large-system headroom, and the 125-gallon filter guide for true large-canister capacity, cabinet fit and service-workflow decisions.
Quick answer
Use this order of decisions:
- Start with the manufacturer aquarium-capacity range. Eliminate models that are not rated for your aquarium.
- Read what the flow number actually means. GPH or LPH may be labeled pump output, maximum flow, filter circulation or simply flow rate; those terms are not automatically interchangeable.
- Treat turnover as context, not a universal prescription. Dividing a published flow figure by actual water volume gives a useful comparison ratio, but it does not override the model’s intended aquarium range.
- Check livestock flow tolerance. A filter can be large enough biologically while still producing an unsuitable localized current for calm-water fish, shrimp or fry.
- Compare media capacity and serviceability. More useful mechanical and biological media can matter as much as a larger pump number, provided you can maintain the filter consistently.
- Account for bioload and tank shape. Feeding, waste production, long tanks, dense hardscape and dead spots can change what circulation and media capacity are practical.
- Do not use oversizing to hide a husbandry problem. A larger filter does not instantly cycle a tank or make unsafe stocking safe.
For aquatic-turtle habitats, use the turtle-tank filter guide before applying a generic aquarium turnover discussion: it separates the habitat’s actual water volume from nominal tank size and anchors the flow target in current veterinary care guidance. For discus, use the discus filter guide because manufacturer tank range and media capacity must be balanced against gentle localized current. For goldfish, the goldfish filter guide narrows the choice by documented tank fit, media access and flow control rather than applying one generic turnover multiplier.
If you are still choosing between filter architectures, read our canister filter vs HOB comparison. If HOB is already the choice, compare our best aquarium HOB filters; if Tidal 55 and AC50 are the finalists, use Tidal 55 vs AquaClear 50; if Tidal 55 and AC70 are the finalists, use the Tidal 55 vs AquaClear 70 comparison; if you are choosing between adjacent Tidal sizes, use Tidal 35 vs 55, Tidal 55 vs 75 or Tidal 75 vs 110; for the Tidal 75 versus AC70 step, use Tidal 75 vs AquaClear 70; for the 110-gallon class, use Tidal 110 vs AquaClear 110; for the 10–20 gallon Fluval overlap, use AquaClear 20 vs 30; for the 20–30 gallon Fluval overlap, use AquaClear 30 vs 50; for the 40–50 gallon Fluval overlap, use AquaClear 50 vs 70; for the 60–70 gallon Fluval overlap, use AquaClear 70 vs 110. Otherwise see the broader best aquarium filters guide.
Start with the manufacturer aquarium-capacity range
The first sizing question is not “what turnover number do I want?” It is “which models does the manufacturer actually specify for an aquarium of this size?”
That range is useful because it is tied to the manufacturer’s design intent for the complete filter rather than to pump output alone. It can reflect the pump, housing, media arrangement and intended use of the model family. It is still not a stocking guarantee — a 50-gallon rating does not mean every possible 50-gallon livestock load is appropriate — but it is a stronger starting boundary than importing one generic GPH formula across brands.
Manufacturer ranges often overlap. Fluval’s current AC Series, for example, lists the AC30 for 10–30 US gal, AC50 for 20–50 US gal and AC70 for 40–70 US gal. A 25-gallon aquarium therefore falls inside more than one model range. The right choice then depends on flow, media capacity, livestock and maintenance, not on the gallon number alone.
The same overlap occurs in canister families. Fluval lists the 107 for 10–30 US gal, the 207 for 20–45 US gal and the 307 for 40–70 US gal. A 40-gallon aquarium is near the upper end of the 207 range and also at the lower end of the 307 range, so the decision needs a second step rather than an automatic “always buy the bigger one” rule.
Why GPH and LPH are not enough by themselves
GPH means gallons per hour and LPH means liters per hour. Those units tell you a volume of water moved per unit of time, but the usefulness of the number depends on what was measured.
A manufacturer may publish:
- pump output;
- maximum flow rate;
- filter circulation;
- a nominal flow rate for the complete filter;
- an adjustable flow range.
Those labels are not synonyms. Before comparing two products, check whether both numbers describe the same kind of measurement.
A high flow number also does not tell you how much mechanical or biological media the filter holds. A compact power filter and a multi-basket canister can post similar-looking GPH figures while providing very different media volume, access and return-flow geometry. Our aquarium filter media guide explains why that media capacity matters beyond pump speed.
Pump output is not always filter circulation
Fluval’s current 07 Series provides a clear example because it publishes both numbers.
For the Fluval 207, the manufacturer lists:
- aquarium capacity: 20–45 US gal / 60–220 L;
- pump output at 120 V / 60 Hz: 206 GPH / 780 LPH;
- filter circulation at 120 V / 60 Hz: 121 GPH / 460 LPH;
- basket volume: 1.8 L;
- total chamber volume: 3.1 L.
If you divided pump output by a 45-gallon nominal tank, the simple ratio would be about 4.6 tank volumes per hour. If you used Fluval’s published filter-circulation figure instead, the ratio would be about 2.7. Both calculations use an official number for the same filter, but they answer different questions.
That does not mean the 207 is incorrectly sized for a 45-gallon aquarium. Fluval itself specifies the 207 for 20–45 US gal. The lesson is that a turnover number is only meaningful when you know which flow specification you put into the formula.
The 07 Series manual also states that its filter-circulation rates were measured with intake and output hoses of the same length. That is useful context because the plumbing arrangement is part of the measurement, not an abstract pump number detached from the filter.
Manufacturer sizing examples
The current examples below are useful because the manufacturers publish both an aquarium range and a flow specification, but they do not all label the flow number the same way.
| Filter | Type | Manufacturer aquarium range | Published flow | Manufacturer label | What the example shows |
|---|---|---|---|---|---|
| Fluval 207 | Canister | 20–45 US gal / 60–220 L | 206 GPH pump output; 121 GPH filter circulation | Pump Output + Filter Circulation | One filter can legitimately have two different published flow numbers |
| Seachem Tidal 55 | HOB | Up to 55 US gal / 200 L | 250 GPH / 1000 L/h | Flow Rate | Capacity and flow are published together for the model |
| Fluval AC50 | HOB | 20–50 US gal / 76–190 L | 200 GPH / 757 LPH | Max. Flow Rate | “Max flow” should not be silently treated as the same label as canister filter circulation |
| Marineland Penguin PRO 275 | HOB | up to 50 US gal | 275 GPH | Flow rate | The model number/flow figure does not mean a 275-gallon tank rating |
These specifications are not a leaderboard. A 275 GPH HOB is not automatically “better” than a 206 GPH canister, because the filters differ in media architecture, measurement labels, return design and intended aquarium range.
The table is also why PetGearReport does not publish one cross-brand formula that converts every GPH number into a definitive tank size. Use the manufacturer’s capacity range first, then use the flow figure to understand and compare the models within that boundary.
Aquarium filter flow reference: current manufacturer labels
Manufacturer pages checked September 23, 2026. This reference keeps each company’s own terminology intact. It is a current specification reference, not a universal turnover target, performance ranking or claim about installed flow in a specific aquarium.
The useful pattern is capacity range first, manufacturer flow label second. Do not normalize these manufacturer labels into one supposedly equivalent GPH metric: Max. Flow Rate, Pump Output, Filter Circulation and Flow Rate describe values that the manufacturers publish under different labels and, in some cases, different measurement conditions.
For a tank-specific calculation, use the aquarium filter sizing & flow calculator. For product selection, use the best aquarium filters guide, HOB filter guide or canister filter guide after confirming that the exact model’s documented capacity includes the aquarium.
Fluval AC Series: aquarium range + Max. Flow Rate
Fluval currently publishes the five AC models below with an aquarium-capacity range and Max. Flow Rate. These are HOB filters with adjustable flow; the GPH number below remains attached to Fluval’s own label rather than being recast as measured in-tank circulation.
| Model | Manufacturer aquarium capacity | Manufacturer flow specification |
|---|---|---|
| AC20 | 5–20 US gal / 18–76 L | 100 GPH / 379 LPH — Max. Flow Rate |
| AC30 | 10–30 US gal / 38–114 L | 150 GPH / 568 LPH — Max. Flow Rate |
| AC50 | 20–50 US gal / 76–190 L | 200 GPH / 757 LPH — Max. Flow Rate |
| AC70 | 40–70 US gal / 152–265 L | 300 GPH / 1136 LPH — Max. Flow Rate |
| AC110 | 60–110 US gal / 227–416 L | 500 GPH / 1892 LPH — Max. Flow Rate |
The overlapping ranges are intentional data, not a recommendation to always buy the larger unit. For example, a 40-gallon aquarium is inside the AC50 range and at the lower boundary of the AC70 range. Flow tolerance, media needs, physical fit and maintenance determine whether moving up solves a real problem.
Fluval 07 Series: Pump Output is separate from Filter Circulation
Fluval’s 07 Series is the clearest reason not to strip the label from a GPH number. The manufacturer publishes Pump Output and Filter Circulation separately for the same model.
| Model | Manufacturer aquarium capacity | Pump Output (120 V / 60 Hz) | Filter Circulation (120 V / 60 Hz) |
|---|---|---|---|
| 107 | 10–30 US gal / 40–130 L | 145 GPH / 550 LPH | 95 GPH / 360 LPH |
| 207 | 20–45 US gal / 60–220 L | 206 GPH / 780 LPH | 121 GPH / 460 LPH |
| 307 | 40–70 US gal / 90–330 L | 303 GPH / 1150 LPH | 206 GPH / 780 LPH |
| 407 | 50–100 US gal / 150–500 L | 383 GPH / 1450 LPH | 245 GPH / 930 LPH |
This shows why one model can legitimately publish more than one official GPH value. A turnover calculation based on Pump Output is not numerically interchangeable with one based on Filter Circulation. Keep the label with the value and compare like with like.
Seachem Tidal Series: upper capacity + Flow Rate + Filter Volume
Seachem currently publishes an upper aquarium capacity rather than a lower-and-upper range for the Tidal family. PetGearReport therefore does not invent a lower capacity boundary. The company also publishes Flow Rate and Filter Volume, which helps keep hydraulic capacity and media-space context visible together.
| Model | Manufacturer aquarium capacity | Flow Rate | Filter Volume |
|---|---|---|---|
| Tidal 35 | Up to 35 US gal / 130 L | 130 GPH / 500 L/h | 0.7 L |
| Tidal 55 | Up to 55 US gal / 200 L | 250 GPH / 1000 L/h | 1.2 L |
| Tidal 75 | Up to 75 US gal / 300 L | 350 GPH / 1500 L/h | 1.9 L |
| Tidal 110 | Up to 110 US gal / 400 L | 450 GPH / 2000 L/h | 3.2 L |
The table is descriptive, not a cross-brand leaderboard. A Tidal Flow Rate should not be silently treated as equivalent to Fluval 07 Filter Circulation or Fluval AC Max. Flow Rate merely because every value can be written in GPH.
How to use this reference
- Find the exact model whose documented capacity includes the aquarium.
- Preserve the manufacturer’s flow label when comparing or calculating.
- Use actual water volume if you calculate a flow-to-volume ratio.
- Compare media volume/architecture, livestock current tolerance, tank geometry and serviceability before choosing between overlapping models.
- Recheck the manufacturer page before purchase or publication because model specifications can change.
The purpose of the reference is to make manufacturer data easier to compare without pretending unlike labels are identical measurements.
How to use turnover without turning it into a rule
Turnover is simply a ratio:
turnover = flow per hour ÷ water volume
If a filter is circulating 200 GPH through 40 gallons of actual water, the arithmetic ratio is 5 tank volumes per hour. That can be useful when comparing two setups or checking how a flow adjustment changes circulation.
The problem begins when the ratio is treated as a universal biological requirement. Filtration performance also depends on:
- how much useful mechanical and biological media the filter provides;
- how evenly water moves through the aquarium;
- how much waste the livestock and feeding routine produce;
- whether the media and intake are clean enough to preserve flow;
- how much current the livestock can comfortably tolerate;
- whether the aquarium is fully cycled;
- how often water changes and other maintenance are performed.
Turnover therefore works best as one diagnostic number, not as permission to ignore the rest of the system.
Nominal tank size versus actual water volume
A “40-gallon aquarium” is a useful product-size label, but the actual water volume can differ once the tank has substrate, rock, wood, equipment and a normal fill level. If you calculate turnover, use the best practical estimate of actual water volume rather than assuming the retail tank label is an exact water measurement.
Do not overcorrect this number with invented displacement percentages. If you do not know the exact volume, a reasonable estimate plus the manufacturer’s own aquarium range is more defensible than pretending the calculation is laboratory-precise.
When to choose the larger model
When two models both include your aquarium in their published range, the larger one can be reasonable when it solves a specific requirement.
Your tank is near the top of the smaller model’s range
A tank at the upper edge of one model and the lower edge of the next model gives you a legitimate choice. The larger unit may offer more media area, a larger intake or more circulation headroom. Compare the exact specification table rather than assuming model names scale in a perfectly linear way.
The aquarium has a higher waste load
More feeding, larger-bodied fish or a higher bioload can increase the amount of solid waste that mechanical media must catch and the biological load the established biofilm must process. A larger media basket can be useful here, but filtration still does not make unsafe stocking risk-free.
The larger model offers better useful media capacity
A larger filter is most valuable when the extra size buys something you need: more reusable mechanical foam, more biological-media space, easier staged media replacement or better service access. Pump speed alone is not the goal.
The flow is adjustable and the livestock can tolerate it
Some HOB filters, including current Fluval AC and Seachem Tidal models, provide flow adjustment. That can make the larger model easier to tune, but verify the exact model’s controls and remember that reducing flow can also change how water passes through the filter.
The tank shape needs more circulation coverage
A long aquarium can have a different circulation problem from a compact tank with the same volume. Intake and return placement, hardscape and plants can create weak-flow areas. In some cases, a larger filter, a second appropriately sized filter or a better return position solves the problem more effectively than chasing one turnover target.
When a larger filter can be the wrong choice
“Buy the biggest filter you can afford” is not a safe universal rule.
The localized current is too strong
Bettas, fry, small shrimp and other calm-water livestock can struggle with strong localized intake or return flow. A filter can be biologically capable and still be a poor match if the animals spend their time fighting the current. Our best aquarium sponge filters guide covers gentler air-driven options for use cases where intake safety and calm flow matter. Axolotls add a species-specific welfare constraint, so the axolotl filter guide separates veterinary gentle-flow guidance from manufacturer hydraulic labels and waste-handling needs. Medium and large cichlid systems introduce a different constraint: the cichlid filter guide weighs debris handling, media capacity and serviceability without assuming all cichlids need the same current.
The filter physically does not fit the setup
HOB filters need rim and rear clearance. Canisters need cabinet or floor space plus safe hose routing. A larger model can create practical problems with lids, braces, furniture, hose bends or maintenance access.
You are compensating for an uncycled aquarium
A larger new filter does not arrive with a mature colony of nitrifying microorganisms. If ammonia or nitrite is present, use our guide to cycling a new aquarium and verify the water with a suitable aquarium test kit. Adding pump output does not instantly create established biological media.
Maintenance becomes harder, so it happens less often
A larger canister with more hoses and media may be technically capable but operationally worse if the owner postpones servicing because access is difficult. A filter that is easy enough to inspect and clean when flow declines can outperform a larger unit that stays clogged.
The real problem is husbandry
Cloudy water, rising nitrate, debris or recurring ammonia should trigger diagnosis rather than automatic upsizing. Check feeding, stocking, dead organic matter, water changes, filter-media condition and cycle status. Our water clarity guide separates particulate, biological and maintenance causes instead of treating all cloudy water as a pump-size problem.
HOB, canister and sponge-filter sizing
Filter architecture changes what “size” means in practice. If the first decision is whether a gentle air-driven sponge or an external canister architecture fits the aquarium, use the sponge filter vs canister comparison before comparing model-size labels.
HOB filters
For a hang-on-back filter, compare the manufacturer’s tank range, maximum or rated flow, media basket/cartridge design, flow adjustment and physical fit on the aquarium rim. Two HOBs with similar GPH can differ substantially in reusable-media volume and serviceability.
Current Seachem Tidal and Fluval AC families both publish overlapping model ranges, which lets an owner choose between adjacent sizes when the aquarium falls in the overlap. Use the livestock’s flow tolerance and the added media/maintenance benefit to decide whether that step up is useful.
Canister filters
Canisters add more variables: pump output, circulation through the complete filter, basket volume, hose routing and head pressure. Do not compare a canister’s pump-output number with a HOB’s maximum-flow number and assume they represent identical operating conditions. A sump return pump is a separate hydraulic decision again: its useful output is the delivered flow at the system’s operating head, not the zero-head maximum on the label.
Canisters can be attractive when extra configurable media space or separate intake/return placement is valuable. They also require more plumbing and a more involved service routine. Our canister vs HOB guide covers those ownership trade-offs separately from sizing; once the architecture is chosen, our best aquarium canister filters guide compares exact canister models. For the smaller 20–30 gallon overlap, use Fluval 107 vs 207. For the overlapping Fluval 207 and 307 ranges, use the Fluval 207 vs 307 comparison; for the next step, use the Fluval 307 vs 407 comparison instead of sizing from pump output alone. For a cross-brand decision at the top of the 07 Series range, Fluval 407 vs OASE BioMaster 2 350 separates manufacturer-specific flow labels, head limits and cabinet geometry. If the OASE platform is already selected, BioMaster 2 350 vs Thermo 350 keeps the filter decision separate from the bundled-heater decision. To compare the top 07 Series model directly with the smallest FX model, use Fluval 407 vs FX2. For larger FX-series systems, the Fluval FX2 vs FX4 comparison separates capacity, filter circulation and cabinet footprint; Fluval FX4 vs OASE BioMaster 2 600 covers the cross-brand cabinet and hydraulic-label trade-off; Fluval FX6 vs OASE BioMaster 2 Thermo 600 adds the larger filtration-envelope and integrated-heater decision; the Fluval FX4 vs FX6 comparison covers the next Fluval-only step where cabinet height and maximum head change materially.
Sponge filters
Air-driven sponge filters are different again. Their aquarium guidance depends on the sponge model plus the air supply driving it. The air pump, water depth, airline arrangement and airflow control affect how much water the filter moves.
Start with the sponge-filter manufacturer’s own tank guidance, then make sure the air pump is suitable for the setup. Do not apply a powered-filter GPH formula to a sponge filter that does not publish water flow in the same way.
Two filters versus one larger filter
Running two filters can add media capacity, more intake/return locations and some operational redundancy, but the ratings should not simply be added together as a stocking allowance.
Two filters may make sense when:
- a long tank benefits from circulation at both ends;
- you want to service one filter while leaving established media running in another;
- one filter architecture handles mechanical debris well while another adds biological-media capacity;
- the combined current remains appropriate for the livestock.
One larger filter may be simpler when it can provide the required media and circulation without creating dead spots or excessive flow. Choose based on the operating system you can maintain, not on the largest combined gallon number printed on boxes.
A practical filter-sizing checklist
Before buying or replacing a filter, answer these questions in order:
- What is the aquarium’s nominal size and best estimate of actual water volume?
- Which exact models include that aquarium in the manufacturer’s published range?
- What does each published flow number mean — pump output, maximum flow, filter circulation or another label?
- How much mechanical and biological media does each model actually provide?
- Does the livestock prefer strong, moderate or gentle localized flow?
- Can the intake be made safe for shrimp, fry or other small animals? If the powered filter is otherwise a fit, our pre-filter sponge guide explains how to measure intake diameter and account for clogging/maintenance without sizing the accessory from tank gallons.
- Will the filter physically fit the rim, cabinet, hoses and lid arrangement?
- Is the tank near the upper end of one model’s range, and if so, what do you gain by moving up?
- Can you access and maintain the larger model consistently?
- Are you trying to solve a sizing problem or a cycling, stocking, feeding or maintenance problem?
Once those answers are clear, use our aquarium maintenance schedule to keep the chosen filter performing without turning every routine check into a full teardown.
Common aquarium filter sizing mistakes
1. Treating one turnover target as a universal minimum
Turnover is a useful ratio, but manufacturers use different capacity ranges and flow labels. Use the exact model documentation first.
2. Comparing unlike GPH figures
Pump output, maximum flow and filter circulation can describe different measurements. Check the specification label before ranking models by a single number.
3. Assuming the model number is the tank rating
The Marineland Penguin PRO 275 is a good example: the manufacturer lists 275 GPH and rates it for up to 50 US gal. The “275” does not mean 275 gallons.
4. Automatically buying one size larger
Moving up can help when the aquarium sits near a range boundary or you need more media capacity, but the larger unit still has to fit the livestock’s flow tolerance and the physical setup.
5. Ignoring media capacity
Biological filtration depends on established biofilm and suitable media, not simply on water moving quickly past an empty chamber. Compare the media design as well as the pump.
6. Sizing from the retail tank label with false precision
The nominal aquarium size is useful for manufacturer ranges, but turnover calculations should recognize that actual water volume may differ after substrate, décor and fill level.
7. Using a bigger filter to compensate for poor maintenance
Clogged mechanical media and dirty intakes can restrict performance. Inspect flow and service the filter according to the exact manufacturer’s guidance instead of treating a bigger purchase as a replacement for maintenance.
8. Using filtration as a stocking formula
A filter rating does not define how many fish an aquarium can safely hold. Stocking also depends on species, adult size, behavior, oxygenation, husbandry and water quality.
A separate circulation pump is not a substitute for correctly sized filtration. If the filter range and media architecture are appropriate but tank geometry still creates low-movement zones, see the aquarium wavemaker and circulation pump guide for placement-first supplemental flow.
Sources
PetGearReport researched current manufacturer specifications for this guide. We did not physically test the filters discussed here, and this page does not use current Amazon prices or customer ratings as evidence.
- Fluval — 07 Series aquarium filters
- Fluval — 07 Series / 207 Canister Filter
- Fluval — AC Series aquarium filters
- Seachem — Compare Tidal Filters
- Marineland — Penguin PRO Power Filter
Frequently asked questions
What size filter do I need for my aquarium?
Start with the exact filter manufacturer's aquarium-capacity range and make sure your tank falls inside it. Then compare the published flow specification, media capacity, livestock flow tolerance, waste load, aquarium shape and maintenance requirements. A turnover calculation can describe flow relative to water volume, but it should not replace the manufacturer's model rating or the needs of the animals in the tank.
How many times per hour should an aquarium filter turn over the tank?
There is no single turnover number that can be applied safely to every aquarium and every filter. Manufacturers publish different aquarium-capacity ranges and even use different flow terms. Use turnover as a comparison metric, then confirm that the exact model is rated for the aquarium and that its current, media capacity and maintenance demands fit the livestock and setup.
Should I buy a filter rated for a bigger tank?
Sometimes, but not automatically. Choosing the next model can add media area or operating headroom when your tank is near the top of a manufacturer's range, but a larger model can also create excessive localized current, take more space or add maintenance complexity. Check the exact model's adjustable-flow features and the flow tolerance of the livestock before sizing up.
Is advertised GPH the same as actual aquarium circulation?
Not necessarily. The label depends on what the manufacturer is measuring. Fluval, for example, publishes both pump output and filter circulation for its 07 Series canisters, and those numbers are different. Compare like with like and read the specification label before using GPH or LPH in a turnover calculation.
Can a bigger filter fix ammonia or nitrite problems?
Not by itself. Ammonia or nitrite can indicate an immature biological filter, disrupted media, excess waste, stocking or feeding problems, or another husbandry issue. Protect established biological media, test the water and correct the underlying cause instead of assuming a larger pump rating alone will make the aquarium safe.