The pond bottom drain was installed after the pond was put in, its a 1 1/2 inch pipe that is about 16-18 inches below the water level, almost flush with the bottom of my "leaf trap". It has about 2 1/2 ft of pipe,(1) elbow and "1" "bulkhead" connection.
My question is this, I am needing to know what amount of water this can deliver "Before" the pump gets ahead of flow rate? If someone had the formula to figure this, that would be great. I may be wrong but I am believe that if I put a deeper "leaf trap" ,and put an elbow with a down pointing pipe I should be able to get higher flow, would this be correct?
I'm not sure I understand the question or your setup. Do you have the bottom drain in a depression and a pipe leading from there up to some sort of skimmer which houses your pump, or do the leaves stay in the leaf trap? And are you thinking of getting a larger pump and so want to be sure that it won't run out of water?
Going deeper into the pond won't increase the flow rate or reduce the friction head of your pipe. Removing the elbow will reduce friction head (turbulence), and it will also eliminate a starting point for clogs. Larger pipe will help on both counts too, but if you're trying to pull debris uphill, you don't want to make the pipe too large.
Assuming your pump is submerged in a box of some sort, and there is no other way for water to enter but the BD line, releasing the water deeper in pump well will allow greater pressure across the pipe and hence a higher flow rate. But at that point, you really need a fatter pipe anyway.
If you're thinking of doing a rebuild, please post a basic diagram or some pictures. Ponding is more complex than it first appears, and there's no reason to repeat the mistakes we've made.
