# Maintaining a constant volume of water in a tank

• KatelynG
In summary, if the pump is operating at a rate of 19 liters per minute, then the hole in the pipe should be no more than 1.5 meters in diameter in order to maintain the same volume of water in tank A.

#### KatelynG

I have water draining from a tank A into a tank B through a hole (or short pipe) and then being pumped back from B to A. If I know the rate of the pump (say 19 liters per minute), what should the diameter of the hole be so that the volume of tank A remains the same? The actual volume of A is arbitrary, so I've started with the assumption that I'll use whatever height gives me a velocity of 1.

KatelynG said:
I have water draining from a tank A into a tank B through a hole (or short pipe) and then being pumped back from B to A. If I know the rate of the pump (say 19 liters per minute), what should the diameter of the hole be so that the volume of tank A remains the same? The actual volume of A is arbitrary, so I've started with the assumption that I'll use whatever height gives me a velocity of 1.
Welcome to the PF.

Weird problem. Can you give us some context? I'd just close off the valves in the system so the levels stay the same.

Doesn't it depend on the height of the water above the hole? I'm not sure what you mean by the height that gives a velocity of 1 ...

berkeman said:
Welcome to the PF.

Weird problem. Can you give us some context? I'd just close off the valves in the system so the levels stay the same.

I'm constructing a fountain of sorts. The idea is that water flows from Tank A to Tank B, then through a filter and then is pumped back to Tank A. Tank A has an open top, and Tank B has a variable amount of water in it, so I can't seal off the system and pull a vacuum.

votingmachine said:
Doesn't it depend on the height of the water above the hole? I'm not sure what you mean by the height that gives a velocity of 1 ...
The equations I started with used the velocity of the water, which is dependent on the volume (height, depth...) of the water, but that's what I'm attempting to maintain as a constant...

float valve?

The easy answer for home construction purposes is an open trough at the top of tank A, that can handle any flow amount into tank B (it simply pours by overflow into B). Or put the pump on an outlet from tank A directly. It sounds like tank B is an extraneous reservoir for filtering purposes. If so then pump from the bottom of A, thru a filter, and back into the top of A.

The flow rate depends on the pressure. You can google and find pipe diameter calculators, but the pressure matters. It matters to the pump also. As the filter gets occluded, the pump will pump at lower flow rates from the back pressure building.

An overflow pipe (like in the back of a toilet tank) will allow tank A to fill, and then handle the variable flow into it with a variable flow out. I don't like the possibility of running tank B dry though, if evaporation happens. Your pump will burn up. Tank B could have a float valve on a water supply, to keep it safe.

KatelynG said:
I have water draining from a tank A into a tank B through a hole (or short pipe) and then being pumped back from B to A. If I know the rate of the pump (say 19 liters per minute), what should the diameter of the hole be so that the volume of tank A remains the same? The actual volume of A is arbitrary, so I've started with the assumption that I'll use whatever height gives me a velocity of 1.

This problem should not be too difficult to analyse .

We need to be clear about the actual arrangement of the tanks , pipe and pump though . Can you post a diagram ?

## 1. How often should I check the water level in my tank?

It is recommended to check the water level in your tank at least once a week. This will help you monitor the water level and make any necessary adjustments to maintain a constant volume.

## 2. What factors can affect the water level in a tank?

The water level in a tank can be affected by a variety of factors such as evaporation, leaks, usage, and temperature changes. It is important to regularly check for these factors to ensure a constant volume of water in the tank.

## 3. How can I prevent water from evaporating in my tank?

To prevent water from evaporating in your tank, you can cover the tank with a lid or use a water conditioner that contains anti-evaporation properties. You can also reduce the water temperature to decrease the rate of evaporation.

## 4. What should I do if I notice a leak in my tank?

If you notice a leak in your tank, it is important to address it immediately. You can repair the leak or replace the tank if necessary. Ignoring a leak can lead to a decrease in water level and potentially damage to your tank and its contents.

## 5. How can I maintain a constant volume of water in my tank during a power outage?

During a power outage, you can use a battery-operated backup pump to maintain a constant volume of water in your tank. You can also manually top off the tank with water as needed until power is restored.