Chizer & Bunoi 67 gallon

[sphelps]

Originally Posted by midgetwaiter

Actually lowering or removing the primary drain standpipe will make life a lot easier in this configuration and it has everything to do with "head". Everybody remembers their first go at trying to adjust a herbie style overflow, even if you did shell out the bucks for a gate valve it can be a complete PITA to try and maintain with the primary standpipe that high.

However if you were to remove the primary drain standpipe and close the valve controlling that drain until the water level in the overflow stays within and inch or so of the top it so it's quiet as well it becomes much easier to do minute adjustments. The reason for this is the pressure built up in the box remains constant when it is at at given level, with a high drain pipe you get much less drain pressure and it fluctuates somewhat making it difficult to adjust. The force of the water is "static head", not to be confused the the "head pressure" we try and work out when sizing a return pump.

Some things to consider in this configuration; When the pump shuts down you will drain the entire overflow box, make sure you have room to catch the water. Also you are at a slightly increased risk of clogging the drain, make sure you open it up once in a while to flush built up gunk. You should be doing that in either configuration though.

Completely false in regards to how pressure works, basic fluid mechanics here guys it's very simple.

Look at these two cases, the static head pressure at the valve (X) is identical for both cases. It's science don't argue with it cause you'll loose

Shortening the pipe will do nothing for pressure and unless you're getting a vertex it will make no difference for adjustment and only result in issues relating to the entire overflow box draining during shut down.