Pump Cycling Rapidly

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After being set up and running for 4 years without any issues, a problem came up recently.

I had air coming out of my faucets suddenly last weekend. I root caused it to a rapid cycling pump due to a blown air cell in a pentair pressure tank. I removed the tank and indeed the air cell had a large hole in it. I replaced the tank with a new AO Smith pressure tank until a replacement air cell can arrive. However the rapid cycling continues even with a new tank...sometimes. See below.

My well pump that runs off a 40/60 pressure switch. After the switch is a sediment filter (main) and dosatron injector unit connected in series. There is a bypass loop around these two using tees and ball values. This loop has just a sediment filter.

If I open the main path (main filter + injector + new tank) the pump cycles rapidly. If I go thru the bypass (sediment filter & new tank) it acts fine.

I've tried bypassing the filter- no change
Removing the injector + filter- no change
Swapping out all the fittings and ball valves- no change
Buying an entire new filter (filter + housing)- no change

It only cycles the pump normally in the bypass loop. Help.


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You want no filter between the pressure switch and the pressure tank.

Maybe post a photo that includes the pipe from the well, the pressure switch, the pressure tank, and the start of the pipe to the house.
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