pool pump pressure

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  #1  
Old 08-30-05, 08:47 AM
m_adkins
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pool pump pressure

I just bought a house with a 25000 gallon vinyl in-ground pool.

Just learning this pool stuff.

The pool is about 20 years old. I have a 48 sq ft Nautalus NSS-48 DE filter and a aqua-flo "A" model 2 HP pump. No check valves. After replacing
the dead pressure gauge I only get about 4 psi at the filter with clean grids and a new load of DE. Flow back to the pool seems strong to me. Is this correct? If not, whats likely wrong.

I had to reassemble the filter grid assembly twice. The first time I was getting some DE settling back in the pool. I'll check this afternoon and see if I got that problem fixed. I did replace one grid that had a 2" tear in it. I need to limp through this season with this filter as I'm really cash poor after buying the house.
 
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  #2  
Old 08-30-05, 08:32 PM
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If the pump you have is an old Aqua Flo “A” series Bronze pump the problem lies within your pump. These pumps use an open faced impeller also made of Bronze. Both the impeller and the housing or valute are worn down, so your pump is not moving a whole lot of water. Putting a new motor on this pump will not help you. Depending on the size of your pool plumbing and the TDH of your pool filtration loop, any of these pumps listed below can move between 3000 to 4000 GPH or more. Get a new ¾ HP new main pump from Hayward (Super 2), Sta-Rite (Max- E-Glass) or a Pentair (Whisper Flow).
 
  #3  
Old 08-30-05, 09:09 PM
m_adkins
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Thanks. Yes, this is a Aqua Flo “A” series bronze pump. I figured a bronze pump would have been a good thing. I'm aware that a bigger motor won't help.

Is it possible to disassemble and check the dimensions of the scroll and impeller and replace the impeller if the pump is otherwise OK? I'm rather handy. I'd need specs to check against though.

The current pump is 2HP. Are you implying that a 25000 gallon pool will work with a 3/4 HP pump? (pool is 18 x 38 x 8' deep vinyl, the 25000 gallon is my estimate)

I assume TDH is the head for the pump (not used to pool acronyms yet). This is a vinyl pool. The pump is on the corner of the deck and the only inlet is the skimmer. Thus, I assume the head is only a couple of feet.

I will also need a new filter after this season. The current Nautalus NSS-48 is past useful life. Just need to limp through the season as cash is thin until my old house sells.

Got any recommendations for a filter?

I don't mind spending money on good pieces, but don't want to buy more than usable.
 
  #4  
Old 08-30-05, 10:20 PM
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You would have to change out the valute the impeller and the shaft seal to get the pump to work ok, its just not worth the time or money. The newer High Head pumps move a lot of water, you can go to the manufactures web side and download the pump curve charts.( a 3/4 Hp Whisper Flow 40' of head moves about 80 GPM or 4800 GPH) New pumps are also energy efficient. I personally like cartridge filters (Pentair or Jandy 300 sf range for a 25,000 gallon pool) they are easier to maintain but I do put in the occasional DE filter.
 
  #5  
Old 08-31-05, 12:25 AM
m_adkins
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Sorry for the elementry questions, I'm new to pools.

I did check on pump parts prices and agree that pump replacement is a better idea.

You didn't give me a good feeling for going with a lower HP pump. Considering my pool size, how does one size a pump. What criteria is used.

If I have 25000 gallons and need to turn the water twice a day, thats 9 GPM. That seems low. (edit: that assumes you run the pump 24/7, probably a bad idea) I have no idea how to calculate head, but it appears that pretty much any HP pump would work. Why then, did the installer put in a 2 hp pump originally. The lower HP pump only saves me $75, so its not the money. I also don't want to overdrive whatever filter I end up with. Why do you recommend a high head pump?


Explain why you like cartridge filters over DE. Every pool owner I checked with locally (sample of 5) uses DE. I live in the So Cal desert and we have a bit of windblown dirt. Don't know if that matters.

Thanks for helping a newbie...

Mike
 
  #6  
Old 08-31-05, 06:48 PM
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Mike, There are several factors in pool hydraulics when sizing a pump. A lot of pool companies or pool stores will just throw in any pump or filter on any pool. I make a good living fixing other pool companies, pool stores & other pool builder’s mistakes. So I size up every thing to work for that particular pool. If you live in a dusty area DE can be better, DE filters also take longer to clean and can make a mess when you break it down to clean it. With a little help from you I can try to give you a better understanding of proper pump sizing. First let me know the size of your pool suction and return lines? Are they copper or pvc? Then we can go from there.
 
  #7  
Old 09-01-05, 10:10 AM
m_adkins
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Originally Posted by pool_guru
Mike, There are several factors in pool hydraulics when sizing a pump. A lot of pool companies or pool stores will just throw in any pump or filter on any pool. I make a good living fixing other pool companies, pool stores & other pool builder’s mistakes. So I size up every thing to work for that particular pool. If you live in a dusty area DE can be better, DE filters also take longer to clean and can make a mess when you break it down to clean it. With a little help from you I can try to give you a better understanding of proper pump sizing. First let me know the size of your pool suction and return lines? Are they copper or pvc? Then we can go from there.
Forgive me for being skeptical, but since your recommendation is counter to what is already installed, it makes me wonder. Your recommendation does seem to be supported by other info I've found on the net regarding pump size, so it sounds like this is the correct path.

Filter:

This is where I've read that bigger is better. You don't want to over drive the filter with the pump. Err on the side of too big. My current filter is 48 sq ft. Should I upgrade to 60 sq ft?

When you said DE takes longer to clean, did you mean filter maintainance or how long it takes to clean the pool (pump run time).

I don't mind the mess of DE if its the right technology. I've disassembled the filter twice now and its not too bad. My issue with DE in the pool has gone away. Apparently I didn't pay enough attention to detail assembling it the filter the first time and had some gaps between the manifold and grids. I got alot of DE in the pool. After vacuuming it three times, the DE seems to be staying in the filter now. I still need to replace the filter as its 20 years old.

Back to the pump...

Lines are PVC. I'll need to double check, but if I can recall off the top of my head, I remember a reducer between the pump and the suction piping. Thus, I would conclude I have a 2" pump and a 1.5 inch suction (and return) line. Pump is located about 10 feet from corner of pool opposite skimmer. Pool inlet is same corner of pool as pump.

I can see a 3/4 HP pump working for filtration, but what about vacuuming?

I also have a inlet for a "Creepy Crawly", but its not in service and I don't know the size. (ain't used pools fun?)


Thanks for taking the time to respond.

Edit: Plumbing is 1 1/2", Pump is 2".
 

Last edited by m_adkins; 09-01-05 at 06:39 PM.
  #8  
Old 09-03-05, 07:48 PM
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before you go off the deep end , the impeller may need adjusting, there are 3 set screws in the shaft extension, look in the open area in front of the pot., [ the pot holds the basket ] loosen the 3 set screws and move the impeller foward [ it may move foward own as the motor seal has a spring in it, at any rate move it back just enough to turn without making a scraping noise, [ were talking thousands of a inch here ] you should see a difference in the amount of water being moved and also a rise in the filter psi,

if after adjusting the impeller you see water leaking from the seal , this is indicative of a new impeller being necessary.


steve
 
  #9  
Old 09-04-05, 02:00 PM
m_adkins
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Originally Posted by stevie3x
before you go off the deep end , the impeller may need adjusting, there are 3 set screws in the shaft extension, look in the open area in front of the pot., [ the pot holds the basket ] loosen the 3 set screws and move the impeller foward [ it may move foward own as the motor seal has a spring in it, at any rate move it back just enough to turn without making a scraping noise, [ were talking thousands of a inch here ] you should see a difference in the amount of water being moved and also a rise in the filter psi,

if after adjusting the impeller you see water leaking from the seal , this is indicative of a new impeller being necessary.


steve
I will look. I assume this is between the motor and the impeller and on the dry side of things?

Thanks.
 
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