U Siphon Vs. Bell Siphon For Aquaponics Systems

Last Updated on October 30, 2022 by Cinthia

Siphon mechanism with regards to aquaponics or hydroponics is an interesting operation. You’re probably wondering which is better when it comes to U siphon vs. bell siphon. This post will educate you on that.

Siphon has been in use for thousands of years. The process of siphon may look mystical. But it’s basically the concept of science at its best. The scientists have concluded that siphon makes use of the key force “gravity.”

It might be pretty confusing to decide between the U siphon and bell siphon method. However, let’s get a good understanding of both mechanisms and make a decision.

U Siphon vs. Bell Siphon
5 Top Feed Drip System Hydroponics
5 Top Feed Drip System Hydroponics

Even though U siphon is convenient, super easy to install, and flexible, and bell siphon may not be so easy to fix- Most hydroponics growers prefer to make use of bell siphon to regulate the flow of water throughout the entire system.

The outstanding advantage between the U siphon and bell siphon is the installation. A U siphon being easy to install makes it a great choice for beginners. However, a bell siphon is faster and has an excellent draining ability.

Better understandings of these two siphon methods will allow us to decide which to go for. Therefore, let’s dive into the mechanism of U siphon and bell siphon.

Mechanism of Bell Siphon for Aquaponics

The bell siphon allows water to fill inside the grow bed. After the water is filled up, the bell siphon drains out water from the grow bed. Bell siphon always sustains a moderate water range and drains excess water back into the reservoir.

The bell siphon operates automatically. It saves you the hassle of manually turning on and off the pump of the flood and drain process. Here is how it works:

  • Stage 1 (Filling): through the water inlet, water floods continuously into the grow bed filling it up from the water pump.
  • Stage 1 (Water lock): when the water fills up the stand siphon pipe to the point of overflow, water begins flowing down through the drain tube and form a water lock. By this time, the air left in the cup has been sucked out.
  • Stage 3 (Drain): water now drains or flows out of the grow beds. Water from the cup is now sucked out after draining water to a particular level.
  • Stage 4 (Breaking siphon): now as the water drains out and drops down to the level of the bottom siphon pipe, air enters inside. This relieves or breaks up the siphon pipe pressure and stop the drain of water.

Aquaponics Auto Bell Siphon Kit 6″ Media or Smaller Grow Bed Mini Garden

This process keeps on going by filling water into your grow bed and siphons it out. The flood and drain process continues for an unlimited time except the pump is stopped.

Mechanism of U Siphon for Aquaponics

Like we mentioned earlier, the U siphon is very easy to install unlike the bell siphon making it a great option for beginners.

The main component of the U siphon is the PVC pipe that drains your growing bed. U siphon pipe has an angle of 45, 90, 90, 45 degrees elbow and a straight pipe. The adjustable U siphon PVC pipe brings in water and the water level does not exceed the loop height.

The U siphon supplies water in and out of your grow bed. When the water level in your grows bed rises, the water level in your U siphon also rises. The curvature end of the pipe contains air. With the motion of water, this air is drawn out and it activates a suction effect.

Once the level of water gets to the loop or curvature of the U shaped pipe, water flows out and siphons out by suction effect. Now your entire grow bed drains out rapidly from the elbow through the siphon process.

Mechanism of U Siphon for Aquaponics

Read more about Best Plants for Small Aquaponics


How do you make a bell siphon for aquaponics?

The bell siphon is the device that takes water from the bottom of the fish tank and transfers it into the grow bed.

The first thing that comes to mind is a simple water trap (e.g. see this). You can use a similar design, but with a bigger hole and a larger diameter pipe to get the water out of the tank. Then, you'd have a small chamber where the bell siphons.

Making a bell siphon for aquaponics is not as easy as you might think. The first problem is that the shape of your tubing determines how much water will flow through it. You need to choose a shape that allows for more water flow than you need to run your system. If you are designing your own, you will have to calculate how much flow you need to run your system, and then design your tubing so that it can handle that flow.

The second problem is that the diameter of your tubing has to be chosen based on the amount of flow you want. If you have a garden hose with a 5/8" diameter, you can't run a garden hose with a 1/2" diameter through it without clogging it up. There is a point where your tubing will have to get smaller than the size of the hole in which it is installed, and this will make it impossible to run a continuous stream of water.

How do I install a bell siphon for aquaponics?

If you have a bell siphon already, and want to add a bell siphon, you should be able to just follow these steps:

1. Take off the old siphon. (You can do this with a pair of pliers.)

2. Take off the top half of the old siphon. (This is the part that will go into your new bell siphon)

3. Make sure there is no water in the old siphon.

4. Make sure that the bell siphon has no holes or cracks in it.

5. Make sure that the bell siphon has a hole that fits perfectly into the bottom half of the old siphon.

6. Put the top half of the old siphon back on.

1. Place the new bell siphon over the hole in the bottom half of the old siphon.

2. Fill the bell siphon with water.

3. Put the top half of the old siphon back on.

4. Put the lid on the bell siphon.

5. Make sure there is no air inside the bell siphon. (Air will make the bell siphon not work.)

6. If you put a little dish soap in the water, it will help to clean out any water or sediment from the bell siphon.

7. If you use a lot of dish soap, it can get into the siphon. Then, it will stop the bell siphon from working.

8. If you do not want to use dish soap, just turn off the water in the kitchen sink and let the water sit in there overnight. The water will clear itself out.

9. Turn on the faucet and slowly turn on the water. (You may need to turn on the cold water first.) This will make sure that the bell siphon does not get clogged up.

10. When the water is at the right temperature, slowly start turning on the water to fill the bell siphon.

11. Wait until the water is full.

Which is better U siphon or bell siphon for aquaponics?

I have a 10 gallon tank with about 6 plants in it. I'm new to aquaponics and am wondering if I should get a bell siphon (which will be used for the water flow) or a u siphon (which will be used for my fish). I've looked at other aquaponics forums and most people are using a bell siphon but some are saying that a u siphon is better. What's the difference between the two?

The bell siphon has a long neck that connects to the tank while the u siphon has a short neck that connects to the tank. The bell siphon is for the water flow, and the U siphon is for the fish. If you only have one of those, you will have to find some way to do both. 

The answer depends on how you are going to use your system. If it's just a hobby, then probably the U siphon will be fine. However, if you are looking at commercializing your system, I would go with the bell siphon as it allows you to add more fish.

Additional Information

We conclude that between U siphon vs. bell siphon, both U siphon and bell siphon are a great choice. More farmers prefer to make use of bell siphon. However, the obvious advantage is that the U siphon is easier and convenient to install than the bell siphon.

When it comes to aquaponics, for your fish and plants to receive sufficient nutrient quantity, it is important to achieve and sustain the right continuous flow of water. A siphon (be it U or bell siphon) is responsible for this. It is used to drain grow beds and it controls and balances the flow of water throughout the system.

The draining process of siphon allows the availability of nutrients for your plants. It as well facilitates root absorption of oxygen which will help your plants grow excellently well.