Thought i would ask a couple quick questions. I have a start on a 12x10 bog hoping to dig down 18 inches but i think the tree roots are going to win this battle. How many diffusers i would need? What size pump would you recommend? The bog is an add-on this year and I already have two 4,000GPH pumps feeding the header pond for the waterfall and stream.
I guess it depends on the diameter of the pipes you use. I used 2" pvc and ran two of them 10 feet long. My bog is 14' X 5'.
It certainly can't hurt to have more manifold branches.
I will tell you this:
My water level is above my gravel right now (I'll try and explain that later) and I can literally see water percolating up through the gravel everywhere, even in areas where there is no manifold below.
So, this tells me there is even distribution throughout the bog.
My pump is just over 3600 gph and seems perfect as far as how fast it exists the bog.
You don't want it to run too fast through the bog. I think you mentioned 4,000 gph. I think that will also be perfect.
And a note on the water level:
Let me see if I can explain this.
I was flushing my manifolds via the clean-out stacks. I do one at a time.
I had left one open by accident for about 20-30 seconds after turning the pump back on.
This highered the water level to a couple of inches above the gravel and spillway.
I turned the pump back off to screw the cap back on the stack, then turned it back on.
Now, since the pump is on, the water level has stayed above the gravel. The pump is keeping it at that level even though it's higher than the spillway.
If I keep the pump off while the "extra" water drains, then turn it back on, it will keep at the level just below the gravel.
Does this make sense? Hopefully!
Water level can be a funny thing.
Imagine letting your bog completely drain back to your pond. Your pond will overflow!
If you turn off your pump and not open the pump output pipe to break the vacuum, the water will be siphoned out of the bog.