Define requirements and constraints
Record the baseline and check measured power rather than label power alone. Do not infer the aquarium's condition from a single sign. Measure the real space, identify connections and preserve clearance for cooling and service.
Then compare annual hours of continuous operation with livestock needs and recent changes. Compare useful capacity, energy and compatibility with the complete setup.
Install for future maintenance
Adjust one variable and assess local unit price and efficiency loss from fouling before continuing. Keep a reference so the result can be compared. Test the assembly under controlled conditions and record settings that must be repeated.
Do not switch essential filtration off to save money; compare efficient pumps at replacement time.