Saltwater AquariumProtein Skimmers, Filtration and Stability
Saltwater aquariums: fish-only and reef tanks, salinity, calcium and alkalinity, nutrient export, the filter room, water changes, the first 12 weeks and UV-C and ozone.
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
- Keep salinity near 35 ppt and temperature 24 to 26 °C.
- Alkalinity, calcium and magnesium must be stable.
- Export nitrate and phosphate with skimming, water changes and good feeding habits.
- Mature the tank slowly, over about 12 weeks.
Two kinds of saltwater tank
Salinity, specific gravity and conductivity
Measure with a refractometer for accuracy. Natural seawater is about 35 ppt. Match top-up water with fresh water (not salt) to replace evaporation.
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
Check your reef water
| Parameter | Reef target | Practical range |
|---|---|---|
| Salinity | 35 ppt | 32 to 35 ppt |
| Temperature | 24 to 28 °C | 24 to 26 °C |
| pH | 7.8 to 8.5 | 8.0 to 8.2 |
| Alkalinity | 7 to 11 dKH | 7 to 9 dKH |
| Nitrate | Low | Below 10 mg/L |
| Phosphate | Very low | Below 0.1 mg/L |
Recommendations vary, especially for nitrate and phosphate.
Keeping calcium and alkalinity up, nutrients down
Corals use calcium and alkalinity as they grow. Replace them with dosing or calcium reactors, and export nitrate and phosphate with protein skimming, refugiums, carbon and water changes.
The filter room under the tank
Sumps, protein skimmers and reactors sit below the display. For large systems use a drum filter instead of filter socks. See drum filter vs sump.
Pure water in, old water out
Use RO or similarly purified water for mixing. Change a modest share regularly. See water changes.
The first 12 weeks of a reef tank
- Weeks 1 to 4Cycle with live rock and ammonia source.
- Weeks 4 to 8Add clean-up crew.
- Weeks 8 to 12Add fish gradually, then corals.
Uv-c and ozone
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.
Saltwater Aquarium FAQ
What salinity should a reef tank have?
About 35 ppt.
Do I need a skimmer?
For most reefs yes.
How often to change water?
Small regular changes are best.
More guides related to saltwater aquarium
Discuss your system with Pureflow.
Share your application, operating volume, actual flow, loading and the question you are trying to resolve.