I don't know how well a siphon will work if the outlet end isn't at least 4' lower than the lowest water level that you want it to function at in the pond.

i.e. if the pond water now is at 500' elevation and you want to drop it 8', you'll probably need the outlet to be at 488' elevation.

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3/4 to 1 1/4 ac pond LMB, SMB, PS, BG, RES, CC, YP, Bardello BG, (RBT & Blue Tilapia - seasonal).