[LEFT]I have a Sta Rite 3hp self-priming centrifugal pump drawing from a river for irrigation. Recently it started losing prime between uses. I’ve checked the suction side for leaks and found nothing. I’ve also checked the pressure side with similar results. I’ve replaced the check valve and I’ve opened up the suction line and verified that the check valve is holding. The pump shows no sign of leaking anywhere, especially around the shaft seal. Any suggestions for what I’m missing? I’ve inspected the pickup and it is clear. Once the pump is primed it runs normally and produces normal pressure and volume. I’m stumped and could use some help. [/LEFT]

We moved in this house (build in 1988) last year. We soon noticed the backup sump pump (a battery powered Watchdog Special installed in 2014) always kicked in even after a normal rain, so we had the main pump (an Everbilt model) replaced with a 1/3hp Zoeller. Our basement was flood from the sump this summer in a heavy rain. Trying to troubleshoot the problem, we’ve replaced the main pump with a new 1/3hp Zoeller (just in case of a defective product), cleaned/replaced the check valves and drilled a hole on pipe to prevent airlock. We’ve checked the sump discharge pipe exit to the outdoor storm line to make sure it is not overflowing or blocked. We’ve also cleaned the gutters and downspouts and have downspout extension at least 10 feet from house. With all these done, during a recent heavy rain, while both main pump and backup pump were working the same time, they still cannot keep up the inflow so we had to manually scoop water out of the sump pit. (man that was the longest 20 minutes in our life!) Our house is 300 feet from a pond, sits on a pretty high water table in general. When it rains, water starts to come into the sump pit very quick (about 10 minutes). We’re thinking, if we change to a bigger main pump, something like 1/2 hp Zoeller, do we need to upsize the discharge line exiting our house? The main pump and backup now have their PVC pipes (1 1/2") for about 2 feet up separately (with a check valve in each line) and then wye connect into the same discharge line (1 1/2”), which runs 5 feet vertical/up and 10 feet horizontal then exits from the house. My question is that if we replace with a bigger main pump without upsizing the discharge pipe, when both pumps are running at the same time (and they will!), could there be too much water into too small of a discharge pipe and then a big loss in flow efficiency? Please help! Thanks to all!