Backwashing according to pressure gauge or not?

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sparkwatercleaner
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Postby sparkwatercleaner » Thu 29 Nov, 2007 20:08

I've checked the pipes, and these "unions" seem to be sealed with some sort of plumbing glue. Anyway, I'll try to open the filter when I have some time.


sparkwatercleaner
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Postby sparkwatercleaner » Thu 06 Dec, 2007 14:50

I've made the following test!


1- After having backwashed, saw the pressure gauge.
2- Stopped the pump and set the multiport valve to "closed".
3- Turned on the pump, rapidly saw the gauge, immediately turned off the pump.
4- Set the valve again to "filter".

What I got to know from this was that the maximum pressure my pump could do was 10 psi higher than the pressure at normal filtering, I simulated a completely clogged filter, with no water passing through it. So, in my case, if I wait till the pressure of the filter gets 10 psi higher than the normal filtering pressure , my pump will break down, as there would be no circulation. This means, again, in my case, that I've got to backwash when pressure gets 6 psi higher and no more.

Do you agree (and understand what I explained)???
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mr_clean
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Postby mr_clean » Sat 08 Dec, 2007 23:51

How often do you need to backwash your filter?
sparkwatercleaner
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Postby sparkwatercleaner » Sun 09 Dec, 2007 19:42

How often do you need to backwash your filter?


I run my filter 5 hours a day during swimming season, which comes to be right now here where I live.
I backwash my filter once every 2/3 weeks.
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mr_clean
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Postby mr_clean » Mon 10 Dec, 2007 19:48

what size sand filter do you have? It should tell you on the side of it.
what size pump do you have? it also will tell you.
sparkwatercleaner
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Postby sparkwatercleaner » Wed 12 Dec, 2007 20:10

What d'you mean by size?
It says:
Width D: 430
Height H: 875
Height M: 735
Height N: 655
(I think they are Millimeters)
Flow rate: 7 m3/h
Pool volume: 40.000 liters
Filter sand: 60 kg
Model: Astral - Millenium - 22407



The pump:
HP: 1/2
Flow rate: 7.8 m3/h
Model: Astral - Sena - 25462
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mr_clean
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Postby mr_clean » Thu 13 Dec, 2007 10:54

what Brand? meaning who makes it? Hayward - Pentair?
take a look at this
Hayward filter here is this your filter?

or Pentair filter here
sparkwatercleaner
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Postby sparkwatercleaner » Tue 18 Dec, 2007 19:34

Both the pump and the filter are AstralPool, a Spanish brand.

To see my filter, see this page , select "English" on the bar, select "swimming pools", select "filters", select "sand filters", select "Blow-moulded filters", select "MILLENIUM filter". Mine is the one on the first picture, second on the chart. There is a downloadable "manual" with technical information on its last page.

To see my filter, see the same page, select "pupms", "self-priming pumps", "plastic self-priming pumps" and then "SENA pump". Mine is the second on the list, the 1/2 hp pump.

Note: My filter's gauge has different colors indicating proper pressures. 0.8 bars is in the upper part of the green area of the gauge. But notice that my pump's technical info states that its pressure is 8 m.c.a. which is the same as 0.8 bars. 0.8 bars are 18 psi approximately. The green area goes from 10 psi to 20 psi. When running with a clean filter, the gauge reads 9 psi. I have to backwash approximately at 14 psi.
sparkwatercleaner
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Postby sparkwatercleaner » Wed 16 Jan, 2008 16:50

Anybody has an answer to my question, instead of making more questions?
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Larry
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Re: Backwashing according to pressure gauge or not?

Postby Larry » Thu 17 Jan, 2008 04:08

sparkwatercleaner wrote:I regulary clean my sand filter when the backpressure shown on the gauge is more or less 4 to just 5 psi higher than starting pressure, and all the equipment, togethter with the pool, is new. I've got to do this 'cause if not, the skimmer (just one, it is the only suction device which has its valve open) won't collect the debris because of low suction. Is this ok? Any problem if I do so?
I ask 'cause I've been told just to backwash when the pressure gets 8-10 psi higher.

I backwash my filter once every 2/3 weeks.


We recommend running the filter 6 - 10 hours per day in the summer (or two turnovers, whichever is greater). We also suggest backwashing sand filters every week or 10 days to keep the sand light and "mobile".

According to your specs, the 0.5 hp pump is providing the filter with a flow near its maximum limit so any accumulation of dirt in the filter will result in an immediate drop in backpressure through the filter. In our Mediterranean climate, I would recommend our customer with your setup to:
* run the pump for at least 9 hours a day in the summer
* backwash once a week

Frequent backwashing can be a waste of water and chemicals, but poor circulation is potentially worse. With a pump near the limit of a sand filter's capacity the most frequent problem we encounter is sand loss due to the speed of water flow during backwash. If the filter is losing sand, you should see some grains left behind in the sightglass after backwashing.

A quick inspection after about 6 months of regular use will confirm whether you have any sand loss or not. The Astral filter lid is very easy to remove using the two-handed key they supply with the filter. Sand loss is typically diagnosed by lower filter pressures as the water flow increases through the reduced sand bed.

I hope this answers your questions.

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