To size a biofloc blower, calculate two numbers: the pressure it must overcome (from tank depth plus diffuser and pipe losses) and the airflow it must deliver (from total water volume). Then pick a model that clears both with margin. For a typical 1.2–1.5 m biofloc tank that lands on a single-stage YEBL-1; for 2 m and deeper it moves to a double-stage YEBL-DS. Here is the full method with worked numbers.
Step 1 — Pressure from depth
Water pushes back at roughly 98 mbar per metre of diffuser depth; use 100 mbar/m in the field. Add the diffuser's back-pressure, pipe friction and an ageing margin:
| Component | Typical value (industry guidance) |
|---|---|
| Water column | ~100 mbar per metre |
| Fine-bubble diffuser | 30–50 mbar |
| Pipe + fittings | 10–30 mbar |
| Fouling / ageing margin | 20–40 mbar |
Worked: a 1.4 m tank → 140 + 40 (diffuser) + 20 (pipe) + 30 (margin) = 230 mbar required at the blower. Always pick a model rated above this figure so it runs cool, never at its stall pressure.
Step 2 — Airflow from volume
Two cross-checking methods (both typical industry guidance, not fixed standards):
- Air-per-volume: ~1.0–1.5 m³/hr of air per m³ of water for active biofloc grow-out.
- Mixing power: ~6–10 W/m³ of installed aeration power.
Worked: a 20 m³ tank → 20 × 1.25 = 25 m³/hr of air. Ten such tanks on one header → 250 m³/hr. The mixing-power check gives 200 m³ × 8 W/m³ ≈ 1,600 W ≈ 2.1 HP of air, consistent with a 3 HP class machine. When the two methods disagree, size to the larger and confirm on the pond with a DO meter — the logic is in dissolved oxygen management with blowers.
Step 3 — Don't lose pressure in the pipe
An undersized main quietly eats pressure and overheats the blower. Keep air velocity around 10–15 m/s. Approximate PVC capacities at ~15 m/s:
| Pipe (nominal) | Approx. capacity |
|---|---|
| 25 mm | ~27 m³/hr |
| 40 mm | ~68 m³/hr |
| 50 mm | ~105 m³/hr |
| 63 mm | ~150 m³/hr |
| 90 mm | ~300 m³/hr |
Feed the grid from a looped header, split into branch legs before the diffusers, and step the main up when several tanks share it.
Step 4 — Match a model
Putting it together for the 200 m³, 1.4 m example: 250 m³/hr at ~230 mbar → YEBL-1-270 (3 HP, 270 m³/hr, 250 mbar). Add an identical standby for N+1 redundancy.
| Total volume | Depth | Airflow | Pressure | Model | Family |
|---|---|---|---|---|---|
| 60 m³ | 1.3 m | ~80 m³/hr | 220 mbar | YEBL-1-145 1 HP | single stage |
| 120 m³ | 1.4 m | ~150 m³/hr | 230 mbar | YEBL-1-210 2 HP | single stage |
| 200 m³ | 1.4 m | ~250 m³/hr | 250 mbar | YEBL-1-270 3 HP | single stage |
| 320 m³ | 1.5 m | ~400 m³/hr | 260 mbar | YEBL-1-400 5 HP | single stage |
| 250 m³ | 2.2 m | ~320 m³/hr | 340 mbar | YEBL-DS-320V 7.5 HP | double stage |
Common sizing mistakes
- Sizing on daytime DO, not the pre-dawn low — the pond looks fine at noon and crashes at 4 a.m.
- Ignoring diffuser fouling — with no ageing margin, a clean-day pick stalls once diffusers foul.
- Running the main too small — the blower makes rated pressure at the outlet but the diffusers never see it.
- No standby — a single blower is a single point of total loss.
More failure patterns are catalogued in aeration mistakes that kill shrimp, and the whole-system view is in the biofloc aeration pillar guide. Protect the intake with a proper air filter so airflow never chokes.
Add a headroom margin — and why
Never size a blower to exactly the calculated demand. Three real-world effects erode capacity over a crop, and a margin of roughly 15–20% on airflow and pressure absorbs all three:
- Diffuser fouling raises back-pressure and coarsens bubbles as biofilm builds up, so a clean-day pick can stall late in the crop.
- Rising biomass lifts oxygen demand steadily toward harvest — the tank that was comfortable at stocking is tight in the final month.
- Hot-season air density thins the delivered oxygen mass on the hottest afternoons, exactly when demand peaks.
Sizing with margin is not over-buying; it is buying for the worst hour of the crop rather than the average one.
Worked example 2 — a deep raceway
Take a single lined raceway, 25 m × 4 m × 2.2 m water depth = 220 m³.
- Airflow: 220 × 1.25 ≈ 275 m³/hr
- Pressure: 2.2 m → 220 mbar water + 45 diffuser + 25 pipe + 40 margin ≈ 330 mbar
- Match: the 330 mbar demand rules out a single stage; a YEBL-DS-320V (7.5 HP, 320 m³/hr, 500 mbar) clears both with room to spare, and a YEBL-DS-230 (4 HP, 230 m³/hr, 410 mbar) suits a lighter-stocked version.
This is the pattern to remember: airflow usually keeps you in the single-stage range, but depth is what pushes you into double-stage. Cross-check the DO strategy in dissolved oxygen management with blowers.
Commissioning checklist
Once installed, confirm the sizing on the water before you stock:
- Measure pressure at the blower outlet and compare to your calculation — a big gap means a pipe or diffuser problem.
- Check every diffuser bubbles evenly — a dead zone means an unbalanced header or a blocked drop leg.
- Run a night DO test at trial biomass to confirm the pre-dawn low stays above target.
- Verify the standby starts and the changeover works before you rely on it.
Part-load and turndown
Demand is not constant — it is low at stocking and high at harvest, low by day and high at night. A well-chosen blower has enough turndown to follow that curve without stalling. Two practical tactics: throttle airflow modestly with header valves for gentle day-to-day trimming, or — better on multi-tank farms — split the duty across two smaller machines and stage them, so one runs at low demand and both at the peak. Staging gives cleaner part-load control than throttling one large machine, saves energy, and builds in redundancy at the same time. What it must never do is force the blower to run against a near-closed valve, which drives pressure up and overheats the machine; that is what the pressure margin and correct pipe sizing are there to prevent.
Frequently asked questions
How do I calculate blower pressure for a biofloc tank?
Add ~100 mbar per metre of diffuser depth, 30–50 mbar for the diffuser, 10–30 mbar for pipe friction, and a 20–40 mbar ageing margin. A 1.4 m tank lands near 230 mbar.
How much airflow per tank?
Around 1.0–1.5 m³/hr of air per m³ of water for active biofloc (typical guidance) — a 20 m³ tank needs about 25 m³/hr.
What size blower for 200 m³ of biofloc tanks?
Roughly 250 m³/hr at ~250 mbar — a 3 HP YEBL-1-270 with an identical standby.
See the aquaculture and biofloc application page for the full range.
Get it sized for you
Send tank count, dimensions and depth and we will return airflow, pressure and the exact model with a standby. WhatsApp +91 9311693322 or email sales@yashblowers.org — 24-hour quotes, dispatched from Faridabad.