Freshwater AquariumSetup, Filtration and Water Care
Freshwater aquariums: community, planted and biotope tanks, matching water to fish, stocking, light, nutrients and algae, CO2, water changes and setup.
SYSTEM CONCEPTSee the mechanism.
Understand the duty.
Select a route or a stage to inspect the process. The cutaway explains the equipment and water environment; it is a teaching illustration, not a project drawing.
Manage the display
Record the stock, feeding and operating water volume.
Use the actual operating water volume, stock and feeding programme to establish the life-support review.
- Record the stock, feeding and operating water volume.
- Keep mechanical, biological and gas duties distinct.
- Review quarantine, maintenance access and safe water replacement.
Key takeaways
- Choose a style: community, planted or biotope.
- Match water hardness and pH to your fish.
- Stock by adult size and filtration capacity, not by what fits today.
- Algae means light and nutrients out of balance.
Community, planted or biotope
Match your water to your fish
| Habitat | pH | Character |
|---|---|---|
| Blackwater (Rio Negro) | Below 5.0 | Very soft, acidic |
| Clearwater (tap-like) | 6.5 to 7.5 | Moderate |
| Rift lake (Malawi, Tanganyika) | 7.8 to 8.8 | Hard, alkaline |
Choose fish that suit your tap water, or treat it.
Work with your own numbers.
Use the tools below to explore the relevant arithmetic. Enter measured values or declared assumptions. An estimate does not establish equipment capacity, biological performance or a safe operating limit.
Water-change volume planner
Calculate the volume changed per event and the original-water fraction remaining after repeated equal changes.
Assumptions and limits
Assumes complete mixing between equal changes. Match replacement-water chemistry and temperature; this is not a safe-change prescription or a treatment guarantee.
Flow & turnover planner
Relate a measured water volume to a selected turnover time. Confirm the time from the application and hydraulic design.
Assumptions and limits
A planning allowance is your assumption. This calculation does not choose a filter, prove treatment capacity or account for pump head.
Convert units before you calculate
Planning arithmetic · inputs remain visible for review · example values are not operating recommendations
How many fish fit in your tank?
Count adult size and the filter, not the glass. A guide is a small number of centimetres of adult fish per litre, adjusted for species activity and waste. Build up gradually and watch ammonia and nitrite.
Light, nutrients and algae
How much co₂ is in your tank?
Plants use CO2. Too little limits growth, too much harms fish. Many planted tanks aim for 15 to 30 mg/L, checked with a drop checker. Relate KH and pH to estimate CO2 and stay safe.
Setting up a new tank, step by step
- Place and level the tankStrong stand.
- Add substrate and hardscapeRinse substrate.
- Fill with conditioned waterRemove chlorine.
- Run and cycle the filterSee nitrogen cycle.
- Plant and stock graduallyA few fish at a time.
From canister filter to central filtration
Large setups and fish rooms benefit from central systems. See rack filtration.
Plan around the collection
Use these questions to prepare a project brief or an operating review. Check an item only when the information has been recorded for your installation.
This checklist is a working aid in the current page session, not a saved maintenance record.
Freshwater Aquarium FAQ
How many fish can I keep?
Depends on adult size, filter and feeding. Add slowly.
Do I need CO2?
Only for demanding planted tanks.
Why is my tank green?
Light and nutrients. Reduce both.
More guides related to freshwater aquarium
Discuss your system with Pureflow.
Share your application, operating volume, actual flow, loading and the question you are trying to resolve.