Herbie overflows and gravity fed skimmer?

[untamed]

If you placed only 1 gate valve on the exit of the skimmer, then the water levels in the skimmer and the overflow box would always match...requiring the skimmer to be exactly the right height. Two valves is the way to go. Then, you have indendent control over the water height in the skimmer and over the water height in the overflow box.

The limit, however, is that you will not be able to drive the water height in the skimmer HIGHER than the water height in the overflow box. If your skimmer is too tall, it won't work because you might not be able to get the water high enough in the skimmer body to make the skimmer function properly. So...you can make a skimmer too tall, but not too short.

That is the issue I'm having. I will require the skimmer to be shortened from spec in order for my gravity feed to work.