Here is a simple design to maintain your water level if you do not have a sump filter.
It is an all plastic toilet fill valve mounted inside a four inch PVC pipe with the bottom end capped. The bottom cap needs to be drilled to mount the toilet valve and to provide a connection to the main tank.
The PVC pipe needs to be mounted at the same or close to the same level as the top of the tank. See the picture for clarification. The two blue water lines will remain level to each other. No, you can not mount this under your tank. Yes you can mount this remotely. You can mount this to the back of your tank or you can mount this in your neighbors back yard, just as long as the two blue water levels are the same. The water level in the PVC pipe will dictate where the level in your fish tank will be. If the pipe falls on the floor, that is where your fish tank water will be. Use your best judgement in securing the pipe to whatever...Those few of you (you know who you are) get someone else to do it.

It is an all plastic toilet fill valve mounted inside a four inch PVC pipe with the bottom end capped. The bottom cap needs to be drilled to mount the toilet valve and to provide a connection to the main tank.
The PVC pipe needs to be mounted at the same or close to the same level as the top of the tank. See the picture for clarification. The two blue water lines will remain level to each other. No, you can not mount this under your tank. Yes you can mount this remotely. You can mount this to the back of your tank or you can mount this in your neighbors back yard, just as long as the two blue water levels are the same. The water level in the PVC pipe will dictate where the level in your fish tank will be. If the pipe falls on the floor, that is where your fish tank water will be. Use your best judgement in securing the pipe to whatever...Those few of you (you know who you are) get someone else to do it.

