Tornado in the Skimmer

[DavidD]

I have been helping out a friend of my wife get her pool open this year. She has an 24' round above ground pool. Got it uncovered, cleaned and water balanced but have noticed that every time I remove the skimmer basket, the pump almost sucks the skimmer dry because of the swirling water. Even when vacuuming, I have to remove the hose to let the pump prime itself again. She has informed the that the pump and filter are new, replaced end of last season by a friend of a friends mechanic. :eek: He installed a Meteor 22" sand filter with what appears to be a 1.5 HP Pentair pump. Both units appear to be matched. There is One Skimmer and One return and all pipes are 1 1/2" schedule 40. This size pump seems way oversized to me, does it to anyone else? The pressure coming out of the return would probably knock a kid off their feet.
Is there anything that can be done to prevent the pump from loosing prime and/or reduce the suction?

Dave

[cleancloths]

The simplest thing to do would be to partially close a valve on the discharge side of the pump. This will reduce the flow and will also slightly reduce the energy consumption. It does not harm to a pump to throttle the discharge, but do not do that on the suction side.

[matt4x4]

Sounds to me like the pump is very overpowered, she should have a maximum of 1hp for that pool, probably even a 1/2hp would suffice.
There are several other things to look at too though:
1. How much water is in the pool? it should be AT LEAST half way up the skimmer, any lower and the "tornado" will suck in air.
2. How much sand is in the filter? if there is not enough, you will get a higher pressure at the return.

[DavidD]

Excellent ides on the discharge valve if it becomes a problem. I'm figuring the pool is 13k gallons and the filter is a little over 3/4 full of sand. It "appears" that the guy put the appropriate amount of sand in however it's hard to tell. I'm sure another bag wouldn't fit in there. I brought the water level up to within about an inch or so of the TOP of the skimmer opening to stop it from sucking the skimmer totally dry, now there's just the tornado but only when the basket is removed. If it is in place, the pump doesn't seem to loose prime. I did tell the friend not to backwash until the pressure increased 10 psi in the hopes that too would help things. She had been backwashing every time she turned the pump on.
Being the optimistic person I am, I've tried convincing her that the guy probably meant well and had the mentality that "bigger's better" but that this definitely did not apply to swimming pool pumps. Needless to say, she was quite upset that he had done this since she spent over a $1,000 for the pump/filter and to have it moved from under the deck to the side. I think he also closed the pool for her, and did a great job at that. Either way, I think we can make what she has work for now.

[wrinkleigh]

Mine does the same thing -- the answer -- dont remove the basket unless the pump is off.

[duraleigh]

Somewhat off the subject but just for clarification......

Restricting the flow on the pressure side will increase pressure....subsequently increase the work load (energy consumption) of a constant speed pump.

Restricting the flow from the suction side is okay as well. You get reduced pressure, reduced flow, and reduced work load in a constant speed pump

[NWMNMom]

Can you tell me how one would go about restricting the flow on the suction side of the system stated above? I believe that's what we have and BTW, she was overcharged for that by someone by about $400. Thanks.

[posguy]

Ball valve coming out of the skimmer.
Anthony

[NWMNMom]

Oh thanks! We DO have one, I'm so glad we installed that! Actually installed one on each side, just in case work needed to be done.

[drumr]

Mine does the same thing too (as wrinkleigh and DavidD) when the basket is out and I have a 3/4 hp pump on it, no problems with the basket in.

[cleancloths]

Ball valve coming out of the skimmer.
Anthony


That makes no sense and is a bad way to go. You NEVER want to restrict the inlet to a pump, you always throttle the discharge of a pump. If you restrict the inlet you will likely have bad cavitation and destroy your pump -- DON'T DO IT!!!!

[duraleigh]

I posted in error on this thread.



Restricting the flow on the pressure side will increase pressure....subsequently increase the work load (energy consumption) of a constant speed pump.


increased pressure does not increase the work load.

Restricting the pressure side results in less flow and actually less work (energy) not more as I stated above.

I helped get this thread pretty far off track. Continued discussion about pump flow, etc. should probably head for the china shop.


Back to the original posters question. I run my skimmer ball valves in a half closed position constantly. I do it to increase volume to a dedicated suction line.

[cleancloths]

Back to the original posters question. I run my skimmer ball valves in a half closed position constantly. I do it to increase volume to a dedicated suction line.


I must be really dense as I still don't understand what you said above after reading it several times. I assume you are talking about a valve that is between the skimmer and the INLET to your pump. If you partly close that valve you are decreasing not increasing flow and that is a very bad thing to do to a pump. Am I not understanding what you are saying????

[posguy]

The way I read it is duraleigh has more than one skimmer or maybe a bottom drain. Closing one partially or fully diverts suction the the other.

[hrsdennis]

Hi Dave, since your situation does not involve a second suction line don't jump to installing shut off or ball valves. Shut off valves are good for shutting down the water supply for doing filter maintanance. Not for reducing flow in either suction or return.

Most of the pools we install here in Arizona come with a 1 or a 1 1/2 HP pump. I have not seen a 3/4 or 1/2 in many years. Unless the pool came from Wallmart or Sams Club. The argument for moving water at a slower speed for more efficiant filtering makes sense to me, but when it comes to vacuuming a pool I love the suction of a 1.5HP. A two speed pump makes so much sense to me and I am so suprised that out of the four to five hundred pools I install a year I have yet to see one.

As for the basket, there is never a reason to run the filter with it removed. Most skimmers allow for vacuuming with the basket in place. Either with a small hole under the skimmer opening {Doughboy} or a Hayward vacuum adapter.

If you do need to connect to the bottom of the skimmer, as I have done many times before, use this method. With the pump running hold your vacuum hose over the return fitting and blow all the air out of your hose. Shut the pump off, remove basket and hook up the hose. Turn pump on and you should have very little proplem with prime.

Hope this helps some. Dennis

[DavidD]

Thanks Dennis. I told our friend the same thing, empty the basket quickly and replace it. The real problem is vacuuming and I've solved it as well. By the time we got the skimmer plate in, the skimmer was dry, even before we could hook up the hose! I figured out that the hose fits in the hole in the bottom of the skimmer so I'm having her fill the hose with water then stick it directly in the hole. Seems to work fine. Ball valves are already installed before the pump and after the filter so obviously the guy had some experience.:rolleyes:
Why are the pumps you are installing so oversized? You must admit, a 1-1/2 HP pump for a 13k gallon above ground pool with one return and one skimmer is a little excessive. Think how much more efficient a 3/4 would be, cheaper to operate, quieter and it would still vacuum the stuff off the bottom right? Not to mention avoiding what seems to be a common problem of "Tornados in the skimmer".

[hrsdennis]

David, glad it is working.

I just install what the pool stores sell. I do however prefer cleaning a pool with a high HP pump. As for normal filtering, a 1/2 or 3/4 seems more suited.

I think a two speed might be the best of both worlds.

I never gave the matter much thought until I started reading the comments of users in this forum. I will be doing some testing on my own pool for sure.

Dennis

[DavidD]

I'm sure the "friend of a friends mechanic" got this filter and pump as a package as well. Probably all the pool shop had. Yes, two speed pumps seem to be the way to go. I've already decided that when my 1 HP goes on my pool, I'll put in a two speed.

Dave