Views: 0 Author: Site Editor Publish Time: 2026-06-02 Origin: Site
Selecting a blower for an aeration tank is not only about airflow. One of the most important factors is water depth. In wastewater treatment, aquaculture, fish ponds, and other aeration applications, the blower must push air through water and deliver stable oxygen supply to the diffuser system. The deeper the water, the higher the pressure the blower must overcome.
Many users only focus on air volume when choosing a blower, but pressure is just as important. If the blower pressure is not enough, air cannot reach the diffuser properly. Even if the blower has a large airflow rating, poor pressure matching can lead to weak aeration, unstable bubbles, higher energy consumption, and reduced treatment efficiency.
This article explains how water depth affects blower selection, when to use a side channel blower or side channel blower, and when a Roots blower is more suitable for deep water and large-scale aeration systems.
In an aeration tank, air is usually delivered through pipes and released into water through diffusers or aeration discs. Before air can come out from the diffuser, the blower must overcome the water pressure above the diffuser.
The deeper the diffuser is installed, the more pressure the blower needs to generate.
A simple rule is:
1 meter of water depth is approximately equal to 100 mbar of pressure.
For example, if the aeration disc is installed at a depth of 3 meters, the blower needs to overcome at least about 300 mbar of water pressure. However, this is only the basic pressure requirement. In real systems, additional resistance must also be considered.
These include:
Pipeline pressure loss
Diffuser resistance
Elbows, valves, and fittings
Air filter resistance
System aging and blockage
Safety margin for continuous operation
Therefore, when selecting a blower, the required pressure should not be calculated only by water depth. A reasonable safety margin should always be added.
The basic relationship between water depth and pressure can be understood as follows:
1 meter water depth ≈ 100 mbar
2 meters water depth ≈ 200 mbar
3 meters water depth ≈ 300 mbar
5 meters water depth ≈ 500 mbar
8 meters water depth ≈ 800 mbar
This calculation helps users quickly estimate the minimum pressure needed for aeration.
If the diffuser is installed at 3 meters water depth, the basic water pressure is around 300 mbar.
However, the actual blower pressure should also include pipeline and diffuser resistance. If the diffuser resistance is about 50 mbar and the pipeline loss is about 30 mbar, the total pressure requirement may reach around 380 mbar or more.
In this case, choosing a blower with only 300 mbar pressure is not enough. A blower with a suitable pressure range and stable working performance should be selected.
For a 5-meter-deep tank, the basic water pressure is about 500 mbar. After adding pipe loss and diffuser resistance, the actual pressure requirement may be higher.
At this depth, some side channel blowers or side channel blowers may still be suitable, especially for small and medium aeration tanks. However, if the system requires large airflow or long-term continuous operation, a Roots blower may be a better choice.
For shallow and medium-depth aeration applications, side channel blowers and side channel blowers are often practical options. They are commonly used in small wastewater treatment systems, fish ponds, aquaculture tanks, and medium-sized aeration pools.
Generally, for water depths from 1 to 5 meters, a side channel blower or side channel blower can be considered.
Side channel blowers and side channel blowers are suitable for:
Small wastewater treatment tanks
Medium-sized aeration tanks
Fish ponds
Aquaculture ponds
Biofloc systems
Small sewage treatment equipment
Industrial water aeration
Oxygen supply for biological treatment
These applications usually require stable airflow, moderate pressure, compact installation, and low maintenance.
Side channel blowers are widely used because they are compact, clean, and easy to install. For many small and medium aeration systems, they provide a practical balance between pressure, airflow, and operating cost.
Main advantages include:
Oil-free air supply
Compact structure
Low maintenance requirement
Stable airflow
Easy installation
Suitable for continuous operation
Lower noise compared with some large blower systems
Good choice for small and medium aeration projects
For users who need a clean and stable air source, a side channel blower is often a reliable solution.
A side channel blower is suitable when the aeration system does not require extremely high pressure or very large airflow. It works well in shallow and medium-depth water where stable air supply is more important than extremely high pressure output.
A side channel blower can be a good choice when:
The water depth is around 1 to 5 meters
The tank size is small or medium
The pipeline is not too long
The diffuser resistance is moderate
The system needs oil-free air
The user wants low maintenance
The installation space is limited
For example, in a fish pond or small wastewater aeration tank, a side channel blower can provide stable air for oxygen supply and water circulation.
When the water depth is greater than 5 meters, especially in large aeration tanks or long pipeline systems, a Roots blower is usually more suitable.
This is because deeper water requires higher pressure. At the same time, large wastewater treatment systems often need higher airflow. Roots blowers are designed for higher pressure and larger air volume, making them suitable for demanding aeration conditions.
Roots blowers are commonly used in:
Large wastewater treatment plants
Deep aeration tanks
Long-distance air supply systems
Large biological treatment systems
Industrial sewage treatment
Centralized aeration systems
High airflow demand applications
In these systems, pressure stability and airflow capacity are very important. A Roots blower can usually provide stronger pressure performance for deep water aeration.
For deep water aeration, the blower must maintain stable pressure for a long time. If the pressure is too low, air cannot be delivered effectively to the diffuser. If the blower is forced to work near its limit for a long time, it may overheat or suffer from reduced service life.
Roots blowers are better suited for deep water because they offer:
Higher pressure capability
Larger airflow capacity
Stable performance under heavy load
Better suitability for long pipelines
Stronger adaptability to large aeration tanks
Reliable operation for continuous industrial use
For water depths above 5 meters, especially when the system is large, it is safer to consider a Roots blower.
The following guide can help users make a basic judgment before detailed blower selection.
For 1 to 3 meters of water depth, side channel blowers or side channel blowers are usually suitable.
This range is common in:
Fish ponds
Small aquaculture tanks
Shallow wastewater tanks
Small biological treatment systems
At this depth, pressure requirements are relatively moderate. A side channel blower can often provide stable aeration with clean, oil-free airflow.
For 3 to 5 meters of water depth, side channel blowers or side channel blowers may still be suitable, but the selection should be more careful.
The actual choice depends on:
Required airflow
Pipeline length
Diffuser type
Number of aeration discs
Operating time
System pressure loss
If the tank is small or medium-sized and the airflow demand is not too high, a side channel blower can still be considered. If the system requires larger airflow or the pipeline is long, a Roots blower may be more reliable.
For water depths above 5 meters, a Roots blower is usually recommended.
This is especially true when:
The tank is large
The pipeline is long
There are many diffusers
The system runs continuously
High airflow is required
Stable pressure is critical
In these conditions, the Roots blower has better pressure and airflow performance.
Water depth is the first factor, but it is not the only factor. In real aeration systems, air must pass through filters, pipes, elbows, valves, and diffusers before entering the water. Each component adds resistance.
If this resistance is not considered, the selected blower may be too small.
Pressure loss can come from:
Long pipelines
Small pipe diameter
Too many elbows
Blocked filters
High-resistance diffusers
Check valves
Silencers
Poor pipeline layout
A well-designed pipeline can reduce pressure loss and improve blower efficiency. On the other hand, a poorly designed pipeline can make even a suitable blower perform poorly.
Diffusers or aeration discs also require pressure to release air. Different diffuser types have different resistance levels. Fine bubble diffusers usually provide better oxygen transfer efficiency, but they may also create higher resistance than coarse bubble diffusers.
When selecting a blower, the diffuser’s pressure loss should always be included in the calculation.
Although this article focuses on water depth and pressure, airflow is also essential. The blower must provide enough air for oxygen transfer.
If the pressure is enough but the airflow is too small, the aeration effect will still be weak. If the airflow is too large but the pressure is not enough, the air may not pass through the diffuser properly.
A correct blower selection should match both:
Required pressure
Required airflow
Only when both values are suitable can the aeration system work efficiently.
Before choosing a blower, users should collect basic system information. This makes the selection more accurate and avoids over-sizing or under-sizing.
Useful information includes:
Water depth
Tank size
Number of diffusers
Diffuser installation depth
Required airflow
Pipe length
Pipe diameter
Number of elbows and valves
Working hours per day
Application type
Environmental conditions
With this information, the blower supplier can recommend a more suitable model.
Some users select blowers only by motor power, such as 1.5 kW, 2.2 kW, or 4 kW. This is not accurate.
The same motor power may have different airflow and pressure curves depending on the blower design. A correct selection should be based on the performance curve, not only the motor power.
The most important parameters are:
Airflow at the required pressure
Maximum pressure
Working point
Motor power
Temperature rise
Continuous operation capability
For small and medium aeration systems, the selection can be simplified as follows:
Shallow water and small scale: choose a side channel blower or side channel blower
Medium water depth: choose according to airflow, pipe loss, and diffuser resistance
Deep water and large airflow: choose a Roots blower
Long pipeline systems: Roots blower is usually safer
Clean and oil-free air demand: side channel blower is a good option
Continuous heavy-duty aeration: select a blower with enough pressure margin
When choosing a blower for an aeration tank, water depth is one of the most important factors. The deeper the water, the higher the pressure the blower must overcome.
A simple reference is that 1 meter of water depth requires about 100 mbar of pressure. If the diffuser is installed at 3 meters depth, the blower must overcome at least around 300 mbar of water pressure. In real systems, pipeline loss and diffuser resistance must also be added.
For 1 to 5 meters of shallow or medium-depth aeration tanks, fish ponds, and aquaculture systems, side channel blowers or side channel blowers can often be considered. They are compact, oil-free, low-maintenance, and suitable for many small and medium applications.
For water depths above 5 meters, especially in large aeration tanks, long pipeline systems, or high airflow applications, Roots blowers are usually more suitable.
In simple terms:
For shallow water and small to medium systems, choose a side channel blower or side channel blower. For deep water, large airflow, and long-term aeration, a Roots blower is usually the better choice.
