What is the biggest sand filter for our pool/pump?

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singerteacher

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Jun 2, 2008
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western Wisconsin
I've been reading TFP posts about getting the smallest pump with the biggest filter for the cleanest water and best efficiency, and I need advice. I'm ready to get a new filter (current Hayward S200 leaks due to hairline cracks around the dome, and Hayward no longer sells just the top half). I would like to buy the biggest sand filter I can, because we have fine silt that our filter can't clear without added DE, and I believe a bigger filter will help with that. (We're also have problems with rust-colored dust returning to the pool after the pump has been off, which hopefully will be solved by the new filter.)

Pump specs:
AOSmith Century Centurion B128
1 HP, 1.40 SF, 1 PH
60 HZ, 3450 RPM, 230/115 volts, SF7.2/14.4 amps
It has just one speed.

Our piping is 1 1/2" and we have a Jandy Legacy LRZ gas heater. That's it -- no fountains, spas, slides.

Please help. I tried reading the hydraulics sticky on the subject and it's way over my head. Pool stores are recommending filters by sand amount, suggesting I go with a 250# sand filter. I think I want more cleaning ability. Thanks in advance!
 
I would suggest that you size the filter based on the pump.

I suggest finding the flow rate of the pump at 20 ft of head, then using the following equation.

√(F x 3.05) = radius of filter in inches.

For example if the flow is 60 gpm at 20 feet of head.

√(60 x 3.05) = 13.5 inches radius or about 27 inches diameter.

The information you gave is for the motor. Do you know what pump you have or have a picture?
 
That's a SuperPump. The TR100 should work for you.

I usually recommend dividing the pump's maximum flow by about 15 to get the surface area of sand required.

The TR100 has 4.91 sqft, which is good for about 74 gpm.

A Hayward sand filter with the same surface area would also work.

A Hayward S310S with a Hayward SP0715X62 Side Mount Pro Series Multiport Backwash Valve would also work.
 
Trying to put this into plain English: We have a 1hp motor connected to a 1.5hp capacity pump, correct? Which means we are pumping water through at no more than 1hp, because that's the max of the motor, correct or wrong? If correct, the 1 hp motor connected to a 1.5hp pump creates a water flow rate at 20 feet away from the motor of ____gpm (a number that you figured out magically somehow). And you used that flow rate to calculate the maximum surface area of sand that our motor/pump combo could effectively push water through, using a less-magical formula of max gpm / 15 = surface area.

If so, I think I might understand this better now. However, I'm still confused by why the pool stores I've talked to never mention the surface area, but instead talk about pounds of sand. Are they the same thing?
 
The total hp of the motor is the rated hp x the service factor. So, 1 x 1.4 = 1.4 total hp. However, that doesn't exactly match any SuperPump.

You probably have a SP2607C or a SP2610C impeller. The impeller size dictates the pump curve and power requirements.

Every pump has a published curve that is a graph of how the flow changes based on the total head loss in feet of head.

Feet of head can be measured by the pressure gauge and a vacuum gauge.

Feet of head is not related to pipe length. At least not directly.

Feet of head is the equivalent distance the pump would have to pump straight up to equal the resistance of moving the water through the pipes. 1 psi is equal to 2.31 feet of head.

When sizing a filter, I try to size at 15 gpm per square foot of filter surface area so that you get a proper backwash.

If backwash flow rates are way above 15 gpm/sqft, the sand gets blown out with the dirt.

If backwash flow rates are way below 15 gpm/sqft, then the dirt is not effectively removed.

During backwash, there is little head loss because the waste line is usually open. This means that the pump will be far to the right on its curve and near maximum flow rate.

During filtering, the flow will be lower, which is good for catching debris.

You can't go too slow during filtering but you can go too fast. Going too fast pushes dirt through the sand and reduces filter effectiveness.

Pounds of sand really doesn't mean much but the larger surface area typically correlates to more pounds of sand.

You could use a 3.14 square foot filter if you don’t want a bigger filter. Many people use that size and it works OK. I think that it’s a bit undersized, but if you have a SP2607C impeller, it would be ok.

If you have a SP2610C impeller, then 4 to 5 square feet is better.

hayward-super-pump-curve.jpg


Hayward Super Pump 1 HP Single Speed - SP2607X10 - INYOPools.com

The SP2607 has a flow rate of about 75 gpm at 30 feet of head.

The SP2610 has a flow rate of about 85 gpm at about 35 feet of head.
 

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Your pump should have more than enough suction unless the filter pressure was over about 20 psi. If you’re not getting enough suction, then it’s probably a configuration issue.
 
Since it used to have great suction, and now is just okay, I don't see how it could be configuration. The changes have been a diffferent pool pump (maybe too big for our filter?) and most recently, hairline cracks with small leaks in the sand filter.

Is there a way to figure out which impeller we have, without taking apart the pump?

The three filters that were recommended to us by pool pros are waaay too small. So, we are looking at asking either replacing the filter ourselves or talking the pool pros into a different filter. We have some experience with plumbing. Is replacing it ourselves advisable?
 
You could generate a pump curve to figure out the impeller by matching it to a published curve, but it's more complicated than just checking the impeller.

The TR100 has 4.91 sqft, which is a good choice for either impeller.

The suction should be fine regardless of the impeller. Maybe it's a clogged suction line. Maybe check vacuum pressure with a vacuum gauge.

You should be able to install it yourself if you can plumb pvc.
 
Re: Changing sand filter ourselves. Do filter companies make this easier by keeping the pipe fittings in approximately the same height? I'm looking at our old Hayward S200 and the Hayward S310S, and thinking maybe the pipes are at the same height so there would be not as much re-routing? Or maybe there are adjustable bases so you can get the unit at the right height for your current fittings? Perhaps this is just wishful thinking ...
 
Due to space limitations between our heater and our pump/motor, it looks like our choices for a sand filter are limited to the Pentair Triton II TR-60, or the Hayward ProSeries S244T. Both of them have a width of 24.5", and our space is tight right now with our Hayward S200 at 23.5" width. Both would increase our effective filtration area from 2.20sf to 3.14sf. However, both of them are 1" wider than our current Hayward S200.

Is this going to make a huge difference? Or are we better off either: 1) sticking with a smaller filter that fits our space exactly, or 2) hiring a pro who can make the extensive plumbing changes?
 
You can stick with the same size if you like the performance. However, you seemed to indicate that you wanted a bigger filter.

I think that a bigger filter is better, but you can go with the smaller one if you feel like the replumb will be too difficult.

I think that I would go with the biggest one that you can reasonably fit.
 

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