| If this is your first visit, be sure to check out the FAQ by clicking the link above.
You may have to register before you can post: click the register link above to proceed.
To start viewing messages, select the forum that you want to visit from the selection below.
|
20-01-2004, 12:02 PM
|
#1
|
|
|
Which Sand filter? (inground pool)
I am having a heck of a time finding an answer. I have a 13,500 gallon
pebble tec freeform pool. I.A 763 surface area of 435square feet. 82 foot
perimeter.
I am going to replace the Jacuzzi cartridge filter with a sand filter(
Hayward, Pentair,sta-rite...other suggestions appreciated), filled with one
of the Zeotype medias.
BUT I cant figure out what SIZE filter to buy..
18/24/30?
Is there somewhere to determine this online? I have been told three
different things by different dealers.
Thanks
Brandon
|
|
|
|
|
20-01-2004, 12:03 PM
|
#2
|
|
|
Re: Which Sand filter? (inground pool)
Brandon wrote:
> I am having a heck of a time finding an answer. I have a 13,500
> gallon pebble tec freeform pool. I.A 763 surface area of 435square
> feet. 82 foot perimeter.
> I am going to replace the Jacuzzi cartridge filter with a sand filter(
> Hayward, Pentair,sta-rite...other suggestions appreciated), filled
> with one of the Zeotype medias.
> BUT I cant figure out what SIZE filter to buy..
> 18/24/30?
> Is there somewhere to determine this online? I have been told three
> different things by different dealers.
>
> Thanks
> Brandon
http://www.pested.msu.edu/BullSlide.../E2621chap8.pdf
|
|
|
|
|
20-01-2004, 12:03 PM
|
#3
|
|
|
Re: Which Sand filter? (inground pool)
"Travis Jordan" <no.one@no.net> wrote in message
news:e9Lwb.66946$86.956173@twister.tampabay.rr.com ...
> Brandon wrote:
> > I am having a heck of a time finding an answer. I have a 13,500
> > gallon pebble tec freeform pool. I.A 763 surface area of 435square
> > feet. 82 foot perimeter.
> > I am going to replace the Jacuzzi cartridge filter with a sand filter(
> > Hayward, Pentair,sta-rite...other suggestions appreciated), filled
> > with one of the Zeotype medias.
> > BUT I cant figure out what SIZE filter to buy..
> > 18/24/30?
> > Is there somewhere to determine this online? I have been told three
> > different things by different dealers.
>
> http://www.pested.msu.edu/BullSlide.../E2621chap8.pdf
The above link is pretty good. However, you need to know a little more. You
can calculate what your water flow SHOULD be to turn the water through the
filter in X number of hours. However, your pump may produce way more or way
less flow than what you calculate. The sand filter may also have more head
pressure than the cartridges you have now. This will reduce the flow rate
from the pump you're using now.
The good news is your pool is rather small, so a 40 GPM pump and a small
filter is probably sufficient. My pool has an undersize filter for the pump
that is installed. I've bought the next larger size bacause it will better
handle the 50 GPM rate my pump provides. The filter I had before was rated
at 40 GPM.
My triton filter has its suggested flow rate as part of the model number
(TR-40, TR-50, ...). You'll need to visit the website for the filter you
want to buy and see what size is required for the water flow rate you have.
May also want to find the specifications of the pump you have now and see
what flow it does with your existing head pressure, and a head pressure 10
PSI higher than what you have now.
--
Mark
Kent, WA
|
|
|
|
|
20-01-2004, 12:03 PM
|
#4
|
|
|
Re: Which Sand filter? (inground pool)
"Travis Jordan" <no.one@no.net> wrote in message
news:e9Lwb.66946$86.956173@twister.tampabay.rr.com ...
> Brandon wrote:
> > I am having a heck of a time finding an answer. I have a 13,500
> > gallon pebble tec freeform pool. I.A 763 surface area of 435square
> > feet. 82 foot perimeter.
> > I am going to replace the Jacuzzi cartridge filter with a sand filter(
> > Hayward, Pentair,sta-rite...other suggestions appreciated), filled
> > with one of the Zeotype medias.
> > BUT I cant figure out what SIZE filter to buy..
> > 18/24/30?
> > Is there somewhere to determine this online? I have been told three
> > different things by different dealers.
> >
> > Thanks
> > Brandon
>
> http://www.pested.msu.edu/BullSlide.../E2621chap8.pdf
>
>
Thanks Travis !
|
|
|
|
|
20-01-2004, 12:03 PM
|
#5
|
|
|
Re: Which Sand filter? (inground pool)
"Mark or Sue" <NOSPAM!suetools@comcast.net> wrote in message
news:1qNwb.229403$275.865227@attbi_s53...
> "Travis Jordan" <no.one@no.net> wrote in message
> news:e9Lwb.66946$86.956173@twister.tampabay.rr.com ...
> > Brandon wrote:
> > > I am having a heck of a time finding an answer. I have a 13,500
> > > gallon pebble tec freeform pool. I.A 763 surface area of 435square
> > > feet. 82 foot perimeter.
> > > I am going to replace the Jacuzzi cartridge filter with a sand filter(
> > > Hayward, Pentair,sta-rite...other suggestions appreciated), filled
> > > with one of the Zeotype medias.
> > > BUT I cant figure out what SIZE filter to buy..
> > > 18/24/30?
> > > Is there somewhere to determine this online? I have been told three
> > > different things by different dealers.
> >
> >
http://www.pested.msu.edu/BullSlide.../E2621chap8.pdf
>
> The above link is pretty good. However, you need to know a little more.
You
> can calculate what your water flow SHOULD be to turn the water through the
> filter in X number of hours. However, your pump may produce way more or
way
> less flow than what you calculate. The sand filter may also have more head
> pressure than the cartridges you have now. This will reduce the flow rate
> from the pump you're using now.
>
> The good news is your pool is rather small, so a 40 GPM pump and a small
> filter is probably sufficient. My pool has an undersize filter for the
pump
> that is installed. I've bought the next larger size bacause it will better
> handle the 50 GPM rate my pump provides. The filter I had before was rated
> at 40 GPM.
>
> My triton filter has its suggested flow rate as part of the model number
> (TR-40, TR-50, ...). You'll need to visit the website for the filter you
> want to buy and see what size is required for the water flow rate you
have.
> May also want to find the specifications of the pump you have now and see
> what flow it does with your existing head pressure, and a head pressure 10
> PSI higher than what you have now.
>
> --
> Mark
> Kent, WA
Ok, so, lets say the pool is 14K gallons.
According to the link that Travis provided...
I could circulate the entire pool in...
3 hours at a flow rate of 77.78 GPM
4 hours at a flow rate of 58.33
5 hours at a flow rate of 46.67
6 hours at a flow rate of 38.89
So I need to find a filter that will handle the capacity that I want. If I
want the whole thing circulated in 3 hours, then I need a filter AND a pump
that will move that much water correct ?
Now what happens if I have a filter that will handle 60 GPM and a pump
pushing 85 gallons per minute?
In other words, can you oversize the pump to the filter, and what
happens?( or doesn't happen)?
Thanks
Brandon
|
|
|
|
|
20-01-2004, 12:03 PM
|
#6
|
|
|
Re: Which Sand filter? (inground pool)
"Brandon" <bnd-66@cox.netthefish> wrote in message
news:dTNwb.21475$m24.21096@fed1read02...
>
> Ok, so, lets say the pool is 14K gallons.
> According to the link that Travis provided...
> I could circulate the entire pool in...
> 3 hours at a flow rate of 77.78 GPM
> 4 hours at a flow rate of 58.33
> 5 hours at a flow rate of 46.67
> 6 hours at a flow rate of 38.89
>
> So I need to find a filter that will handle the capacity that I want. If
I
> want the whole thing circulated in 3 hours, then I need a filter AND a
pump
> that will move that much water correct ?
Yes. And its a circultar solution because the filter head pressure affects
how much water your pump can pump. Most pumps have appalingly flat curves,
which means a slight change in head pressure can have a dramatic effect on
flow rates.
> Now what happens if I have a filter that will handle 60 GPM and a pump
> pushing 85 gallons per minute?
> In other words, can you oversize the pump to the filter, and what
> happens?( or doesn't happen)?
Good question. The head pressure caused by the filter will increase as flow
increases, but this isn't necessarily bad. If you pump more water through
the filter than it is rated for, I believe filter performance (quality) will
diminish. Another problem I have is that when backwashing, the pressure is
really low so the pump flows even more than when filtering. I'm just on the
edge of cavitating my pump when backwashing. If I bypass the filter directly
to waste, the pump does cavitate so I can't do that. It is better to have a
filter that slightly exceeds your pump capacity than the other way around.
Personally, I think it is better to have a pump running longer at low flow
than a huge one that filters the whole pool in two hours. There are times
when you want to run the pump all of the time (freezing conditions, algae
blooms), and a giant one will cost you more to run during those times. It
also takes time for the water to mix well and the things in it to stratify.
This again makes long and slow better than short and fast.
Finally, realize that there is a speed limit in water pipes. If the pump
intake from the pool skimmer is 1.5" PVC pipe, you shouldn't flow more than
60 GPM through that pipe. Otherwise, it will deteriorate faster due to water
friction. For some reason, pressure pipes have a slightly higher speed limit
than suction pipes, but for pools the suction pipe is usually the limiting
factor.
--
Mark
Kent, WA
|
|
|
|
|
20-01-2004, 12:05 PM
|
#7
|
|
|
Re: Which Sand filter? (inground pool)
"Mark or Sue" <NOSPAM!suetools@comcast.net> wrote in message
news:1iPwb.306614$Fm2.324871@attbi_s04...
> "Brandon" <bnd-66@cox.netthefish> wrote in message
> news:dTNwb.21475$m24.21096@fed1read02...
> >
> > Ok, so, lets say the pool is 14K gallons.
> > According to the link that Travis provided...
> > I could circulate the entire pool in...
> > 3 hours at a flow rate of 77.78 GPM
> > 4 hours at a flow rate of 58.33
> > 5 hours at a flow rate of 46.67
> > 6 hours at a flow rate of 38.89
> >
> > So I need to find a filter that will handle the capacity that I want.
If
> I
> > want the whole thing circulated in 3 hours, then I need a filter AND a
> pump
> > that will move that much water correct ?
>
> Yes. And its a circultar solution because the filter head pressure affects
> how much water your pump can pump. Most pumps have appalingly flat curves,
> which means a slight change in head pressure can have a dramatic effect on
> flow rates.
I am still at a bit of a loss on what head pressure is, and what changes
it. I am assuming it is directly affected by flow rate through the filter.
I.E when the sand is dirty, you head pressure increases, correct? So, when
you backwash and the sand is clean, that is "normal" as read on the pressure
gauge?
I ordered a Hayward 310T( I got it for 355 delivered, a heck of a deal
considering everyone else I found was 400 plus freight), just because it is
rated at 92 GPM. I am leaning towards a 1 hp Pentair whisperflo pump which
will push at about 82GPM at 20 feet of head( I have 2" plumbing).
Any thoughts?
Thanks for all the information you have offered. It is much appreciated.
Brandon
> > Now what happens if I have a filter that will handle 60 GPM and a pump
> > pushing 85 gallons per minute?
> > In other words, can you oversize the pump to the filter, and what
> > happens?( or doesn't happen)?
>
> Good question. The head pressure caused by the filter will increase as
flow
> increases, but this isn't necessarily bad. If you pump more water through
> the filter than it is rated for, I believe filter performance (quality)
will
> diminish. Another problem I have is that when backwashing, the pressure is
> really low so the pump flows even more than when filtering. I'm just on
the
> edge of cavitating my pump when backwashing. If I bypass the filter
directly
> to waste, the pump does cavitate so I can't do that. It is better to have
a
> filter that slightly exceeds your pump capacity than the other way around.
>
> Personally, I think it is better to have a pump running longer at low flow
> than a huge one that filters the whole pool in two hours. There are times
> when you want to run the pump all of the time (freezing conditions, algae
> blooms), and a giant one will cost you more to run during those times. It
> also takes time for the water to mix well and the things in it to
stratify.
> This again makes long and slow better than short and fast.
>
> Finally, realize that there is a speed limit in water pipes. If the pump
> intake from the pool skimmer is 1.5" PVC pipe, you shouldn't flow more
than
> 60 GPM through that pipe. Otherwise, it will deteriorate faster due to
water
> friction. For some reason, pressure pipes have a slightly higher speed
limit
> than suction pipes, but for pools the suction pipe is usually the limiting
> factor.
>
> --
> Mark
> Kent, WA
>
>
>
|
|
|
|
|
20-01-2004, 12:05 PM
|
#8
|
|
|
Re: Which Sand filter? (inground pool)
"Brandon" <bnd-66@cox.netthefish> wrote in message
news:240xb.22208$m24.2187@fed1read02...
> "Mark or Sue" <NOSPAM!suetools@comcast.net> wrote in message
> news:1iPwb.306614$Fm2.324871@attbi_s04...
> > Yes. And its a circultar solution because the filter head pressure
affects
> > how much water your pump can pump. Most pumps have appalingly flat
curves,
> > which means a slight change in head pressure can have a dramatic effect
on
> > flow rates.
>
> I am still at a bit of a loss on what head pressure is, and what changes
> it. I am assuming it is directly affected by flow rate through the
filter.
> I.E when the sand is dirty, you head pressure increases, correct? So,
when
> you backwash and the sand is clean, that is "normal" as read on the
pressure
> gauge?
Head pressure is caused by the resistance to flow and is measured in feet of
water or PSI. This is the pressure that must be overcome to move the water.
Pipe length and water flow rate increase head pressure as they increase.
Pipe diameter lowers head pressure as it increases. A filter has a given
head pressure and the manufacturer will state what it is. This is the
"clean" head loss. As the filter becomes dirty, head pressure will increase.
For a sand filter, at 10 PSI more head than normal, it is time to backflush
(so you want a pressure gauge on your filter).
> I ordered a Hayward 310T( I got it for 355 delivered, a heck of a deal
> considering everyone else I found was 400 plus freight), just because it
is
> rated at 92 GPM. I am leaning towards a 1 hp Pentair whisperflo pump
which
> will push at about 82GPM at 20 feet of head( I have 2" plumbing).
>
> Any thoughts?
Glad you have 2" pipes, so you should be able to flow this much water. As I
said before, I think a smaller pump run longer is better than a large one
run faster. My pool is slightly larger than yours (17,000 gal) and I run a
3/4 HP pump at around 50 GPM (actually 30 to 60 GPM depending on head
pressure). When the pump dies, I'll replace it with a 1/2 HP pump that has a
better flow curve (almost always 50 GPM instead of only 50 GPM when the
filter is clean).
That being said, what you propose should work, it will just cost more when
you have a water problem to remedy because you'll need to run it 24 hours a
day for up to a week.
--
Mark
Kent, WA
|
|
|
|
|
20-01-2004, 12:06 PM
|
#9
|
|
|
Re: Which Sand filter? (inground pool)
Mark or Sue writes:
> As I
> said before, I think a smaller pump run longer is better than a large one
> run faster.
Quite true. You will spend $1000s for electricity running this pump, it
pays to get it optimized for power costs. Size it as small as possible to
turn the water over during daylight hours.
|
|
|
|
| Thread Tools |
Search this Thread |
|
|
|
| Display Modes |
 Linear Mode
|
Posting Rules
|
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts
HTML code is Off
|
|
|
All times are GMT +11. The time now is 07:26 AM.
Powered by: vBulletin Version 3.0.3
Copyright ©2000 - 2009, Jelsoft Enterprises Ltd.
The Travel Forum
|
|
|
|
