High Filter Pressure

Hi everyone!

I wanted to detail my recent adventures in pool repair in case someone else has this problem and is looking for help. I found some hints in this forum that led me to the answer, but perhaps more detail will help others.

I have an in-ground colored plaster pool, 18K gallons, with a Purex Triton Seahorse pleated cartridge-type filter (4x 100ft2 cartridges), in-line chlorine tablet feeder, gas heater, Jandy automatic valves, pool/spa pump and Polaris dedicated pump. I had the pool built 9 years ago. Normal filter pressure is 18psi clean, 20 psi with dirty dirty filters. With the valves in spa lineup, I could get 22 psi. Never has it been above 22 psi in 9 years.

Last week, the gage read almost 30 psi. I was in shock. I opened the filter up, and yes, it was dirty, but not THAT bad. I cleaned the cartridges up and reinstalled them. No change in pressure.

I pulled the outlet line out of the filter and ran the pump. No blockage. I ran the unit again, and there was no air in the filter during normal operation, so there were no leaks in the suction. If there was a blockage in the suction line, I'd get low pressure, so I concentrated on the discharge side. I disconnected the inlet/outlet lines from the heater, flow was fine. I bought a new pressure gage, and there was no change in pressure. Now I was starting to worry. There was also a funny noise somewhere.

I had not been using my chlorine feeder, since I am a true believer of the liquid bleach method. I thought perhaps there was a clog in the chlorine feeder, and as I looked at it, I noticed that there was a check valve directly upstream of the feeder. I put my hand on it and could feel vibrations in it, and it turned out that that was the source of the funny noise (like a whistling).

I took a chance. I cut out the feeder and check valve from the line (I had to go about a foot upstream of it to find a place to cut it, and after a 90 degree elbow downstream. I went to buy a new check valve. When I did, the pool store guy gave me a new chlorine feeder connector too. I told him I wasn't going to use the feeder any more, and he got this scared look on his face. How are you going to get chlorine in the pool? he wanted to know. Knowing that I couldn't tell him about the liquid chlorine (I tried to before, but these guys go crazy when they hear about using bleach - "YOU CAN'T PUT UNSTABILIZED BLEACH IN A POOL!!"), I told him I was going to use a tablet floater. He said that then I wouldn't need the check valve at all - that its only purpose was to keep highly chlorinated water from getting into the heater when the pump was off. He said go buy some fittings and pipe and just replace them.

I did that, buying a 90 degree elbow, two connectors, and some 2" pipe, for less than $10. It was a bit of a pain getting the piping in between two fixed points, but I managed.

I let the pipe solvent set up a couple hours, turned the pump on and VOILÀ! 16 psi (the check valve was a 2 psi spring loaded check valve.) I was getting great flow from my system and it was much quieter.

So that's it. It was the check valve all along. and I didn't even know I had one!

wilhouse