If you aren't using the system any more and don't want to use it, why not yank it out of the pond completely? I bet you could sell it and recoup at least 50% of your investment.

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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).