Retrofit bottom drain - install without cutting liner in a running pond

[Usman]

 

[Tula]

Are you planning a retro fit BD?

 

[Mitakuye]

Usman, I have a suggestion. You may find solid accumulation around the pipe, that goes from the drain to your sidewall, and also those 2x 45 degree elbows are adding unnecessary friction loss (head) to your pump.

I would remove the 2x 45 degree elbows. Allow the pipe go straight to the sidewall, to where it connects to the pump. This will raise the pipe above the floor more and reduce friction loss. As shown in the first picture, be sure you are using a long sweeping 90 degree elbow wherever 90 degree elbows are applicable.

 

[Mitakuye]

Usman, for more information, do research on "Solid Lifting Overflow", which best describes your second picture.

 

[Usman]

Are you planning a retro fit BD?

for future plans , i had this design in mind i thought would share and get some more ideas/discussion , it should work same way as conventional BT as there will be syphin in the pipe it will be gravity fed . there are some ready made versions too i found out later-on
most of us want bottom drain but installing in linner is difficult and its done while constructing the pond so it can be substitute

 

[Tula]

Will you use a submersible pump, or external?

 

[Meyer Jordan]

Keep in mind that, because this is a gravity fed device, the pumps flow rate can not exceed the flow rate from the BD.

 

[Mitakuye]

Usman, as a quick warning, do not allow the water velocity in your drain pipe to be below 2 feet per second. A 2 ft per second velocity will prevent fish waste and small bits of algae sedimentation inside the pipe. However, this will not stop sedimentation of much heavier debris in the horizontal pipe, like small twigs. Flow rate and pipe size is what determines your water velocity.

To know your feet per second, this is a good calculator I found. http://www.1728.org/flowrate.htm. Click the "velocity" option below the "do you want to solve for". Then, fill in the appropriate fields.

This applies whether pipes are gravity or pressure fed.

This will increase the friction on the flow, but this means purging the drain line much less often.

If the bottom drain manufacturer indicates a lower flow rate is necessary below 2 feet per second, then I would ignore this recommendation.

I often read odd, sometimes unnecessary, recommendations on these hobby pond products.

 

[Meyer Jordan]

Do not confuse flow rate with velocity. Flow rate is the amount of water flowing through a pipe in a given period of time. Velocity is the speed of the water.

 

[Mitakuye]

Do not confuse flow rate with velocity. Flow rate is the amount of water flowing through a pipe in a given period of time. Velocity is the speed of the water.

Mr. Jordan, velocity can't exist without flow rate. Velocity is a "flow" of water in a given period of time as well.

Flow rate is inferred, required, by velocity.

 

[Mitakuye]

You cannot achieve a velocity in differing pipes without mandating a flow rate in the pipe.

Two are mutually exclusive.

 

[Mitakuye]

If you have flow, then you have velocity.

 

[Mitakuye]

If impacts of velocity was better understood and the impact it has on an entire system, then I would not read so many odd recommendations. One pet peeve that has become a bother to me within the hobby pond world.

 

[Meyer Jordan]

"Volumetric flow rate is the volume of a liquid that passes through a given surface per unit time. It is found from the flow velocity and the surface area of the surface through which the fluid passes."
Boundless. “Flow Rate and Velocity.” Boundless Physics

"Flow rate and velocity are related, but quite different, physical quantities. To make the
distinction clear, think about the flow rate of a river. The greater the velocity of the
water, the greater the flow rate of the river. But flow rate also depends on the size of
the river. A rapid mountain stream carries far less water than the Amazon River in Brazil"
Openstax Rice University

The same flow rate will have a higher velocity in a 2" pipe than it will have in a 3" pipe.

 

[Mitakuye]

"Volumetric flow rate is the volume of a liquid that passes through a given surface per unit time. It is found from the flow velocity and the surface area of the surface through which the fluid passes."
Boundless. “Flow Rate and Velocity.” Boundless Physics

"Flow rate and velocity are related, but quite different, physical quantities. To make the
distinction clear, think about the flow rate of a river. The greater the velocity of the
water, the greater the flow rate of the river. But flow rate also depends on the size of
the river. A rapid mountain stream carries far less water than the Amazon River in Brazil"
Openstax Rice University

The same flow rate will have a higher velocity in a 2" pipe than it will have in a 3" pipe.

I agree and nothing I wrote disputes this and your text reinforces what I wrote. You can not have velocity without flow and vice versa.

Both are expressed in units of time. One is simply volume and other is size.

I challenge you to computate the velocity of water without using flow, and vice versa.

You can't because velocity is also a "flow" of water in a given period of time as well as flow is also a "velocity" of in a given period of time. This does not indicate they are the same physical quantities, nor is it implied.

I never suggested they are similar physical quantities, but they are mutually exclusive expressions in a given period of time.

You are shifting the conversation now away from the bottom drain to prove your point.

The manufacturer defines the "size of the river" with its suction inlet.

You are creating an argument here that should not exist. I am not here to argue nor to defend myself, which seems to be what you want.

This does not help Usman.