Decision essentials
Key points
Loss rises with velocity and restriction.
A fitting can equal metres of straight pipe.
A pump curve is more useful than zero-head flow.
Filtration
Two kinds of head
Vertical difference creates static head; pipe and fittings create friction head. One narrow connector can govern the circuit.
Biofilm and debris shrink effective diameter. Throttling works but intentionally turns pump energy into loss.
Filtration
Optimise in sequence
Fix kinks, trapped air, fouling and redundant fittings, measuring after each change.
Do not modify filter ports beyond manufacturer pressure and sealing limits.
From evidence to action
Decision matrix
| Situation | What to do | Why |
|---|---|---|
| Low from installation | Check lift and diameter | Circuit consumes head |
| Gradual decline | Clean hose and prefilter | Effective bore narrowed |
| Many sharp elbows | Use smoother routing | Every fitting adds loss |
Check the result
After the adjustment, measure flow under the same conditions and check noise, leaks, waste accumulation and circulation. Record the result; if performance drops again, locate the restriction before changing another part of the system. For “Head, hose and elbows: where rated filter flow disappears”, use a pump curve is more useful than zero-head flow as the final article-specific check.
Evidence
Sources and scope
Sources include institutions, technical studies and manufacturers. Chezur separates established mechanisms from editorial decisions for home aquariums.