Prime Comes and Goes - Too much HP?

[happyheathen]

I had the old configuration working (as long as I didn't put the cartridge in the filter). Replaced the filter.

First, is this normal: With pump off, the water level in the skimmer throat is about 2". With the pump running, it is less than 1/2", and the top og the basket is barely covered. Remember - the only floor drain is plumbed into the skimmer, not the pump. I still suspect the floor drain is partially blocked - I couldn't find a jetter, the pressure cleaner I used shot out a handful of small pebbles, and the bladder just sat there - it swelled up, but there was no indication of resistance.

The pump acts normally and starts to fill. When I close the filter's bleed valve, it stabilizes for a while, then drops, raises again - after a few minutes, I can open the bleed valve and find a new supply of air in it.

I hate raising the water level just to have to drain it, but if it sounds like a close-to-dry skimmer is the likely culprit, I will.

Of possible interest: the old filter had the in and out ports at 90 degrees. This one has them at 180.
This install is getting uglier every time I touch it - the line from the pump to the filter is now over 4' horizontal - add another 3' for verticals. 1 1/2 hp on a 200 sq ft cart filter, 2" plumbing.

The cart is used, the backyard dealer I bought it from made sure it was shiny white, but it still registers 10-20 psi CLEAN. Of course, this gauge thinks free air is 20 psi

Does this situation raise any flags?

 

[Bama Rambler]

You have a few things going on. One is the pressure gauge itself. If it reads 20 psi when the pump is off it needs replacing.

Next is if you're constantly getting air into the filter it has to be coming from the pump and sine you say the skimmer is running almost dry, I suspect it's getting in there.

If your MD is plumbed to the skimmer you should have a diverter in the bottom of the skimmer that you can adjust the amount of water between the skimmer and the MD. If you don't, you need one.

Is the skimmer creating a vortex sucking in air when the pump is running?
Are there bubbles in the pump basket when it's running?

 

[happyheathen]

No great swirling, but the water level is a bit lower in the center than the edges.

ETA: no bubbles

I think I just answered the Q about why this didn't show up with the old filter in place - I upgraded the plumbing from 1 1/2 to 2", reducing only for the 1 1/2 lines to/from heater. Probably improved circulation enough for the full capacity to show.
Not mentioned: I installed a 1 1/2 HP because that is what I replaced - the original install had 2 massive solar heating panels on the roof. All that is left are two pipes cut off at the roof sheathing. So why a gas heater as well? Maybe for a toasty spa

There is no diverter, there is no indication of anything ever been installed in the sump. I thought of cutting a chunk of something to block the inlet, but, in addition to being recessed 4-5", there is a large glob of cement dried on the face of inlet - it would be tough to get a waterproof seal with that in place
A quick google on "pool skimmer diverter" produces a couple of different designs - including a flap to block the throat and devices to plug the MD line. Some look like they sit on the bottom of the sump and have a rotating hole to select source. To which are you referring? (Yes, my mother WAS the English teacher from that place we can't mention here)

The more I think about it, the more convinced I am that the pump would much rather take water from the surface than from 7' below it.

 

[mas985]

The more I think about it, the more convinced I am that the pump would much rather take water from the surface than from 7' below it.

Actually, there should not be much of a difference. Static head is determined by the water level not the suction depth. The only difference would be in dynamic head due to the pipe length and fitting differences.

 

[happyheathen]

The more I think about it, the more convinced I am that the pump would much rather take water from the surface than from 7' below it.

Actually, there should not be much of a difference. Static head is determined by the water level not the suction depth. The only difference would be in dynamic head due to the pipe length and fitting differences.

In addition to the additional 8' of pipe, the inlet from the MD is 1 1/4 pipe used as the male on the skimmer's 1 1/4 / 1 1/2 fitting. Why they ran 2" pipe to such a skimmer and why such a skimmer was installed in the first case are Q's I've given up pondering. There is a tile set in the top step identifying the builder. It is no longer doing business around here, under that name.
A foot of water standing on top of its inlet would not require pulling it up.

I have a large amount of assorted crud on the bottom, and it came in handy for a little test I ran.

I took the brush and shoved large clouds of crud near and over the drain. There was no great suction, but the drain did pick it up when it was directly over it. Dropping the cloud off 2-3 feet from the drain caused it to stop moving but it still disappeared within 5 seconds.
Is that a reasonable test of drain power, and did it pass?

The first time I drained it, I was able to drain it completely with the main pump - I have a domed glass pot cover which covered the two holes perfectly. That pump, 2 years ago could raise the water into the dome and then to the pump

           |--- pot cover ---|
         _______________________ skimmer bottom
            ||            ||
            ||            ||
            ||            ||
 pipe from drain      pipe to pump

So I at least know it's not structurally damaged.

 

[happyheathen]

Well, an additional 2-3" of water solved the mystery of disappearing head.

Next Q 0 is it possible for the filter (and a tiny leak therein) explain the bubble of air found after several minutes?

This uses an under-sized o-ring for the body seal - it must be stretched to fit into its groove.
Unfortunately, with the O-ring installed, the locking ring will not fully seat - it needs to turn an additional 30-45 degrees to engage the clamps.
This is Pentair's low priced version of the Clean and Clear - it is black and has ports 180 degrees apart - the C&C is sand colored and has ports more reasonably spaced at 90 degrees

 

[Bama Rambler]

Any air getting into the system while the pump is running has to come from the suction side. Even though raising the water level helped some, if you're still getting air in the filter you still have a leak somewhere on the suction side of the pump. Have you removed and resealed the drain plugs?

 

[happyheathen]

Thanks!

I've been under the weather for the last few days - when I saw the pump's basket full, I was relieved enough to just shut it down and crawl back into bed.
So I don't know if the mystery bubble still occurs in the filter.
There has been no indication of a water leak, and I did remove and re-seat the plug I could remove (the butterfly tabs on the basket plug have been broken off)