Maybe this will help:
Sump filter
This is the most common type of filter used by serious fish keepers. This type of filter is extremely adaptable and flexible. It is not the cheapest, easiest or safest filter but many people think its advantages outweigh its disadvantages. This system can be hard to understand so I have added some common questions people ask me about sumps.
There is a solid PVC pipe mounted inside the tank, usually at one side directly over the sump. There is a hole drilled in the bottom of the tank and the pipe runs strait up through the hole and stops just below the top of the tank. The point that the pipe passes through the tank must be sealed to prevent leaks (usually using a screw on flange). The top of the pipe allows tank water to overflow into it and then pour into the sump underneath. This means that the waterlevel of your tank will always be at or just over the top of the overflow pipe!
Therefore there is NO pump on the overflow! You may use 1 or more pumps for the return.
Bear in mind the following:
Sump filter
This is the most common type of filter used by serious fish keepers. This type of filter is extremely adaptable and flexible. It is not the cheapest, easiest or safest filter but many people think its advantages outweigh its disadvantages. This system can be hard to understand so I have added some common questions people ask me about sumps.
A sump filter under a tank
This system is a sump located under the aquarium. The system by which water gets from the tank to the sump is called an OVERFLOW. There are many types of overflows and I will explain a very common one called a STAND PIPE.
There is a solid PVC pipe mounted inside the tank, usually at one side directly over the sump. There is a hole drilled in the bottom of the tank and the pipe runs strait up through the hole and stops just below the top of the tank. The point that the pipe passes through the tank must be sealed to prevent leaks (usually using a screw on flange). The top of the pipe allows tank water to overflow into it and then pour into the sump underneath. This means that the waterlevel of your tank will always be at or just over the top of the overflow pipe!
Therefore there is NO pump on the overflow! You may use 1 or more pumps for the return.
Cycle is as follows:
- Excess water from tank overflows into the overflow pipe
- Water pours through the overflow pipe into the sump
- Water passes through filter media in sump
- Water pumped from sump into tank at any rate you desire
- Water being pumped into the tank raises the water level of the tank
- Excess water from tank overflows into the overflow pipe
- Cycle continues indefinately
As water is pumped from your sump to the tank it causes the tank to overflow back into the sump - therefore the waterlevel in your sump remains constant. The pump should never run dry.
Bear in mind the following:
- The amount of water in your tank is determined entirely by the position of the overflow. You cannot run your filter with a lower water level in your tank.
- Having a hole drilled in the bottom of your tank is a risky business. Any leaks at the flange will cause your tank to drain entirely. The overflow must be as watertight as the sides of your tank!
- Overflows can be VERY noisy - fortunately you can make a silencer
- If your pump stops then the water in the return pipe and any water above the level of the overflow will drain into your sump (the narrower your overflow pipe the more water there will be). You must allow for this volume of water to be contained by your sump or it will overflow onto the floor! A good way to prevent this is to fill your sump up with the pump turned off. When the pump is turned on the water level will drop a bit then remain stable (it drops very slowly due to evaporation).
