Skimmer flow Question

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C

craigvt

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Sep 22, 2010
8
Hello,
I just purchased a home that came with a swimming pool. I have spent the last week or so watching videos and giving myself a "crash course" in pool maintenance. I need to get everything worked out before I close it for the winter and the lady who owned it before me was clueless. Her husband had left and he was the only one who knew anything about the pool (story for another forum).

In order to effectively answer my question, let me explain my pool setup.
I have a pool that is about 20k gallons that has only one skimmer and one main drain. It has a RETURN vacuum pump port and two return jets.

The maindrain and the skimmer are running off the same intake line (I think?), there is no valve at the front of the pump to regulate the two of them. It has to be done with the flow valve inside the skimmer (again, I think?)

Exiting my pump is two return lines with a valve. The valve regulates the water flow in two directions/return lines. One to my filter and back into the pool, or to the vacuum return port. (I keep it about 3/4 going to the filter and 1/4 going to vacuum port).

My issue is this, when /if I run ONLY the vacuum (valve turned all the way to the vacuum return line and cutting off the filter/return lines), my pump has full prime.

However, If I run the water flow to the filter/return lines and turn the vacuum port return line off, I don’t get the pump at full prime. It’s CLOSE but no cigar. It causes bubbles to spit out into my pool.

Here is the interesting part, If I remove the FLOW VALVE from the bottom of the skimmer (the flying saucer thing that has a hole on the bottom that can be partially covered, closed or open with a sliding flap), the pump will catch full prime. However, shortly thereafter, ALL of the water gets sucked out of the skimmer, it runs dry, than the skimmer fills back up again, and it becomes a vicious cycle doing this over and over. It CAN'T be food for the pump.

So, I’m assuming that it must be the flow valve that is preventing me from running full prime? Also, if I open the flow valve flying saucer hole ALL THE WAY OPEN, the same thing happens (the pump completely drains the skimmer). Could this also be an issue with the water flap on the skimmer throat or the water level? The water is about halfway covers the skimmer throat so I think the water level is good. Maybe the flap on the skimmer throat needs adjustment?

I have a main drain but again, there are no levers to control it at the pump. I’m not even sure where it’s connected. I’m assuming it’s the second hole in the bottom of the skimmer (the hole closer to the pool water that's not sucking anything in)?

Sorry for the long winded question(s). I just wanted to give as much detail as possible since pools have so many configurations and possible issues.

Thanks so much for any help!
 
Welcome to TFP.

We like a lot of info. :)

Your main drain IS connected through your skimmer as you suspected. The diverter is there to allow for dividing the flow between the skimmer and MD.

Your issue with the air getting into the system is a suction side problem. Either air is sucking into the skimmer (as you described) or you have a suction side leak. The first thing I'd do is raise the water level to about 2/3rd's up the skimmer and make sure the weir (water flap) is operating freely and not sticking.

You should be able to run completely from the MD or completely from the skimmer and not suck in air.

Another common place to suck air into the system is the pump strainer basket lid. Remove it and clean the o-ring and groove, then lube the o-ring with silicon pool lube and reinstall it. That should help if that's part of the problem.

P.S. You should only run the vacuum port open when there's a vacuum hooked to it. It's bypassing your filter when it's running and you want all the flow to go through your filter unless vacuuming.
 
Thanks for the info. :party:
My strainer basket doesn't have a top on it at all. It's just a basket with a handle.

Also how do i adjust that diverter to know what is going where? The diverter I have is simply a disc with a hole in the bottom of it (right in the middle) that has a piece of plastic that rotates around so you can move over top of the hole. There is nothing that actually directly covers the holes in the bottom of the skimmer. The diverter covers both of the holes at the bottom of the skimmer when it's placed in the bottom of the skimmer. There is a circular rubber ring a the botom of the skimmer that the diverter fits into. The two holes sit below the diverter. One hole is closer to the pump (the hole that has suction) and the other hole is closer to the water (main drain hole). How would I adjust this diverter and how does it regulate what's going from the main drain and what's coming in from the pool skimmer itself? :hammer:

I guess I can try adding water to the pool to see if that fixes the problem. Basically, the water fills into the skimmer, pump gets primed, then the skimmer creates a tornado and all the water in the skimmer gets sucked down (and fast) completely emptying the skimmer. Then water flows overtop of the throat flap into the skimmer filling the skimmer back up. the skimmer fills back up, the water tornado forms again, sucking the water down...you get the idea :mrgreen:

As for the vacuum return port, I have a vacuum connected to that so it's good to go.
 
Not the strainer in the skimmer, the one on the front of the pump. There should be a large canister on the front of the pump that has a lid on it.

Your skimmer has two holes in the bottom. One goes to the MD and the other goes to the pump (as you've already discovered). [s:wal4nj98]When you move the disc over the open hole it restricts water coming from the MD and more water flows through the throat of the skimmer.[/s:wal4nj98] You partially cover the hole to allow some water from the MD and some through the skimmer. Edited to indicate correct operation of different diverter style. See post below for proper statement.

If the weir is working correctly then adding more water is what's needed. The vortex created is caused from either the weir not working correctly, not being the correct one for the skimmer, or the water level not being high enough. The water level is easy to figure out and fix. At this point it doesn't sound like the pump strainer basket lid is the problem but an inspection of it wouldn't hurt.
 
thanks for the response. Yes the pump basket lid is OK. It works fine and fully primed when using the auto vacuum return port. I keep it nice and tight but not too tight and have emptied it daily for the last week (but barely anything gets in there in the first place, just some fine pine needles).

That's very interesting about moving the plastic over the hole on the diverter actually restricts the flow from the main drain. I would have thought it would be the opposite! My train of thought was that since the main drain hole is below the diverter, and I covered the diverter's hole, than water from the main drain hole would flow directly into the pump intake since that hole is also below the diverter. If the hole on the diverter were open, I would think that the water from the skimmer above the diverter would flow more freely down into the pump intake hole. It's actualy the opposite? :hammer: lol, sorry I still get a little confused over the physics of all of this.

I'll put more water in the pool. The weir seems to be fully operational, it flapps back and forth freely but when the vortex is happening, the door just stays down (open) but I guess water can't flow in the skimmer fast enough or as fast as the pump is pulling it out from the skimmer.

The confusing part is that the pump is primed if I just remove this diverter completely...it's primed for about 30 seconds until the vortex happens. Keep in mind, the vortex doesn't happen when I put the diverter back in the skimmer unless i Have the hole on the diverter completely OPEN. In that case, I still get the vortex from the skimmer.
Thanks :cheers:
 
Can I retract my last statement about the operation of the diverter. :hammer:

I was thinking of a different type. You are right, fully open, the pump draws from the skimmer a lot and the MD only slightly. Fully closed it draws only from the MD. The vortex is created only when drawing a lot of water through the skimmer. Raising the water level is still the answer.
 
The easiest way to figure out the diverter is to play with it. That's what I did. I could see the turbulence/flow in the skimmer without the diverter. Then I set it in with the flap closed and observed, then flap open and observed, then started partially moving it. The way I have mine set now, the movement in the skimmer looks almost the same as with no diverter, yet I know I have flow in the main drain because I can sweep stray leaves and such at it and they will go in. They don't get sucked in, with the anti-whatever cover on the drain, like they would inside the skimmer, but it's definitely pulling water. I can also tell because the water is pretty much the same temperature all the way to the bottom. None of that dip your toe in and think it's nice and warm, then jump in and hit the ice water below.
 
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