pump slowly losing prime

[mas985]

Ben,

I am not sure we are talking about the same thing. This is the stuff I use and for me at least, it doesn't get sticky nor does it dry up so you can easily wipe it off with a rag if you ever need to:

http://www.lesliespool.com/Home/Pump...ies/68926.html

BTW, this is exactly the same stuff as plumber's silicone grease which I have used as well with the same results.

[PoolDoc]

I've used the "Jacks Magic" stuff that's been around in the pool industry for years. It's great for sticking a large O-ring -- that would otherwise jump out -- in place, say on a Challenger pump. But it's also as I said.

I have used the Rainbow chlorinator silicone, and it's not like that. The Leslie's stuff could be more like the Rainbow stuff, in which case it wouldn't be so good on a Pentair Challenger pump back O-ring . . . but it would be much better everywhere else.

[sjpoolowner]

Thank you all. My answers to your questions are:

1. The flow seems strong when I run it at high speed. As mentioned earlier, that's after 95% priming.

2. The filter pressure is 27 psi at 3000 rpm, 29 at 3100 and 31 at 3200. I think the pressure was 10-11 psi when running at 2000 rpm. I have Sta-rite system 2 PLM 200 cartridge filter (200 sq ft). Haven't cleaned it for about 2 years since I didn't notice significant increase in filter pressure yet. I plan to do it before opening the pool this year.

3. I tried to open the filter air valve after turning on the pump. Not much difference observed. I see intermittent clusters of small bubbles coming out of the returns but they seemed to stop after a while.

I decided to run the pump at 3000 rpm for hours and see if that makes any difference. I'll update this afternoon.

Based on the fact that water level in the pump basket is lowering very slowly, it looks to me that pump not being fully primed is a different issue than the air leak? Or are they actually same? Should I suspect clogged suction line as well?

Thanks again. I really appreciate your help.

[sjpoolowner]

Actually, I kept watching the returns after running the pump at 3000 rpm for 15-20 minutes and noticed the bubbles kept coming out. They are very tiny bubbles and not "shot" out of the return. Rather they just float along the wall where the return is. Very intermittent, sometimes I have to wait 10-30 seconds to see another group of bubbles. I also noticed that they come out of only one return, whose water flow is stronger than the other return's.

Does this mean the air trapped in the pump basket is slowly being pushed out and thus a good thing? Or does this merely indicate air is slowly entering into the system? I tried to look into the pump basket to see any bubbles coming from the suction but it was difficult to see inside (the lid not as transparent as I would want it to be and also air pockets made it harder).

I think I am okay even if the pump doesn't fully prime as long as it stays that way and I don't need to re-prime the pump. But I'll have to fix any air leaks.

Thanks a lot.

[mas985]

During the priming process, the pump needs to push the air out of the pump basket into the return line. If there is a suction leak, it will continuously draw air into the pump basket and out the returns. So the continuous air out of the returns is a good indication of an air leak.

You are correct though in that it the pump can operate properly with a small amount of air. But if there gets to be too much air, it can cause pumping issues. A short run at higher speed should take care of that.

[BigDave]

sj,
It seems that while you may have some air leakage, you may also have some restriction that is greatly reducing flow making it difficult to clear the air from your pump basket. I would definitley clean the filter as soon as possible, I'd also open the pump basket to look for any blockage in the impeller (after disconnecting the power of course). I'd then clean the O-ring and its mating surfaces really well and inspect for any damage (scratches etc.) before putting it back together.