When I redid my pipes to add a ball valve to my bio filter circuit I removed a check valve. I didn’t think much about it until I shut off the pump the other day to empty its leaf basket. Since my bio filter sits higher than my pump a wave of water came rushing backwards through the pump and leaf basket chamber. I forgot to close the ball valve to prevent this. Fortunately the prefilter sits higher than the biofilter too so it was at least a slow wave. The water also partially went down my jets line and filled the pond. So I need to reinstall the check valve this weekend.
Plan your pond’s plumbing so that water can only flow in the direction you want. Use a combination of check valves, shut off valves, 3 way valves, ball valves, knife valves, gate valves, or whatever else you need to make sure water can not flow back through the system. Remember to have easy access to valves for back flushing, rerouting, temporary closing of circuits, and maintenance.
UPDATE: I put the swing check valve back in place when I added my UV light. I now have 3 ball valves and a 3 way valve that can control flow back from the filter for drainage purposes but the check valve keeps it from coming back to the pump.
