HUSBANDRY · CONTROLLED DOCUMENT
AE-SOP-0112 — Dynamic Water-Change Protocol
To replace calendar-based water changes with sensor-driven, minimum-effective exchanges computed per tank against species setpoints. The procedure conserves prepared mixing-reservoir water, reduces livestock handling stress, and guarantees that no exchange is performed on a system already in band — every litre moved is justified by a sensor reading.
ActiveHusbandryRev C
1. Purpose
To replace calendar-based water changes with sensor-driven, minimum-effective exchanges computed per tank against species setpoints. The procedure conserves prepared mixing-reservoir water, reduces livestock handling stress, and guarantees that no exchange is performed on a system already in band — every litre moved is justified by a sensor reading.
2. Scope
All holding systems on the AquaLink sensor mesh.
- In scope: Routine husbandry water exchanges, exchange-volume computation, reservoir draw, and post-change verification.
- Out of scope: Emergency exchanges during life-support failure, which follow AE-SOP-0211; forensic sampling of effluent, which follows AE-SOP-0312.
3. Definitions
| Term | Definition |
|---|---|
| Setpoint Band | The species-specific acceptable range for each parameter, outside which an exchange is triggered. |
| Minimum Effective Exchange | The smallest water volume that returns a system to band, computed by NEREID per cycle. |
| Mixing Reservoir | A pre-conditioned water store matched in chemistry to a destination zone. |
| Effluent Sensor | An outflow probe used to verify a system returned to band after an exchange. |
4. Responsibilities
| Role | Responsibility |
|---|---|
| NEREID Liaison (Owner) | Owns the protocol; reviews flagged tanks and tunes setpoint bands per species. |
| Husbandry Operator | Executes computed exchanges and confirms post-change verification readings. |
| Marine Science | Sets and approves the species-specific setpoint bands. |
| NEREID | Evaluates each tank per cycle, computes minimum effective exchange, and skips in-band systems automatically. |
5. Exchange Trigger Setpoints
| Parameter | Target Band | Exchange Trigger | Review Flag |
|---|---|---|---|
| pH | 8.1–8.4 | ± 0.15 from band | > 25 % volume to correct |
| Nitrate | ≤ 10 mg/L | > 15 mg/L | > 30 mg/L |
| Salinity | 33–35 ppt | ± 1.0 ppt from band | > 2.0 ppt drift |
| Temperature | Zone setpoint ± 0.5 °C | ± 1.0 °C | ± 2.0 °C |
Note. Any tank requiring an exchange above the review-flag volume is held for human review before action — large corrections signal an upstream fault, not a routine drift.
6. Materials & Equipment
- AquaLink mesh coverage on every holding system
- Matched mixing reservoirs per destination zone
- Calibrated inflow and effluent sensors
- Metered exchange pumps with volume logging
- Species setpoint-band table (current revision)
- Reservoir level and quality readout
7. Procedure
7.1 Evaluation
- Pull current readings for every tank on the mesh each cycle.
- Compare each parameter against its species-specific setpoint band.
- Skip the change entirely where all parameters are already in band.
7.2 Computation & Exchange
- Compute the smallest exchange volume that returns the system to band.
- Draw from the matched mixing reservoir; confirm reservoir level first.
- Hold any tank needing a change above the review-flag volume for human review.
7.3 Verification
- Verify return to band with effluent sensors after the exchange.
- Log before and after readings against the tank record.
- Flag any tank that fails to return to band for the NEREID Liaison.
8. Records
- Per-tank exchange log with before/after readings (retained 2 years)
- Computed exchange volumes per cycle
- Reservoir draw and level log
- Review-flag exception log
- Setpoint-band revision history
9. References
- AE-SOP-0118 — Overnight Anomaly Sweep
- AE-SOP-0211 — Cold-Water Life-Support Failure Response
- AE-MET-005 — Water Quality
- AE-MET-035 — Reservoir Level
10. Revision History
| Rev | Date | Author | Summary |
|---|---|---|---|
| A | 2088-03-19 | NEREID Liaison | Initial issue; replaced fixed-schedule changes with sensor evaluation. |
| B | 2089-08-02 | NEREID Liaison | Added minimum-effective-volume computation and skip logic. |
| C | 2090-02-02 | NEREID Liaison | Added review-flag thresholds and effluent-sensor post-change verification. |