Auto shut-off valve in under-sink RO systems

[concerned_RO_user]

Hi,

I am preparing to get an under-sink RO system with pressurized storage tank for
both drinking and aquarium use, and have a question about the auto shut-off
(ASO) valves included in most systems.

When the ASO valve is activated it shuts down the input to the RO cartridge and
causes the pressure differential across the membrane to decrease (and maybe even
reverse). If residual water remains in the cartridge, will this situation allow
any significant amout of impurities to pass from the "dirty" side to the "clean"
side of the membrane, especially at night when this condition would last for
many hours?

Would it be better to shut off the flow at the brine (dirty) output of the RO
cartridge rather than the input? If so, are there any valves that would do this
based on the pressure in the storage tank, just like the regular ASO does?

Or am I making a mountain out of a molehill?

Thanks for any info.

[Christ's Soldiers]

In the land of rec.aquaria.marine.reefs the word of the Lord came to
concerned_RO_user and verily he spoke saying:

> Hi,
>
> I am preparing to get an under-sink RO system with pressurized
> storage tank for both drinking and aquarium use...

I have no help to offer but just out of curiosity, I am looking for
the same thing with a tank for drinking water. Where do you find
something like that?

--

-John

Because it makes things difficult to understand.

Why shouldn't I top post?

[Rbogath]

Get a check valve and don't worry about it...

RandalB

[CapFusion]

"Christ's Soldiers" > wrote in message
. 97.132...
> I have no help to offer but just out of curiosity, I am looking for
> the same thing with a tank for drinking water. Where do you find
> something like that?
>

You can get the following -
Marc
http://www.sparklingfloorservice.com/tank/ro_di.html


Or from AquaticReefSystem
http://www.aquaticreefsystems.com/Reverse_Osmosis_4Stage.htm
http://www.aquaticreefsystems.com/Drinking_Water_5Stage.htm

You do not really need a resoviour / pressurized tank to have a drinking
water. You just simply get slow output. The pressure tank will give you
quicker product water + product water directly from your RO.

If you want a pressurized tank and already have a RO [RO/DI], you can get it
from above link or from anywhere else like HomeDepot. You just attach that
tank to your RO product output water line with a "T" valve. The "T" valve
will let you be able to turn off/on the flow when you need it.

CapFusion,...

[Marc Levenson]

If you are overly concerned with TDS creep in your membrane, don't use the first few
minutes worth of water. However, if that water is going to be pumped into a tank,
it would take a lot longer than a few minutes to purge it all out.

I guess I wouldn't worry about it. Compared to the water coming out of the tap, you
are way ahead of the game.

Marc


concerned_RO_user wrote:

> Hi,
>
> I am preparing to get an under-sink RO system with pressurized storage tank for
> both drinking and aquarium use, and have a question about the auto shut-off
> (ASO) valves included in most systems.
>
> When the ASO valve is activated it shuts down the input to the RO cartridge and
> causes the pressure differential across the membrane to decrease (and maybe even
> reverse). If residual water remains in the cartridge, will this situation allow
> any significant amout of impurities to pass from the "dirty" side to the "clean"
> side of the membrane, especially at night when this condition would last for
> many hours?
>
> Would it be better to shut off the flow at the brine (dirty) output of the RO
> cartridge rather than the input? If so, are there any valves that would do this
> based on the pressure in the storage tank, just like the regular ASO does?
>
> Or am I making a mountain out of a molehill?
>
> Thanks for any info.

--
Personal Page: http://www.sparklingfloorservice.com/oanda/index.html
Business Page: http://www.sparklingfloorservice.com
Marine Hobbyist: http://www.melevsreef.com

[Ct Midnite]

Before you go to all the expense of a pressure tank system you need to
think about how you are going to use this thing.

I'm not an expert but from experience with using a pressure tank with
well water I'm questioning how happy you will be with your new system.

If all you want is to have a couple of gallons available when you want
them, maybe 2 at the most, to top off tanks, you will be happy. But
if you think this new system will give you all the RO water you need
to, let's say, fill a new tank or a major water change, you will be
disappointed.

Your new system will give you a couple of gals very quickly and then
slow to a trickle, just like without a pressure tank.

The only way to over come this restriction would be to have a very
large pressure storage tank and all the systems I have seen on the web
work with small ones, 1 or 2 gals. They are really designed for fast
drinking water. When I go to my RO unit and want to fill up my water
jug with water for drinking I have to set my timer on the stove and go
back and get it later. Maybe 15 min / gal. These pressure systems
give about 1 gal/ 20 sec. But not for very long.

Just thought you needed to evaluate what you were really wanting
before spending the money.

Ct Midnite

PS. And in reality I've already quit using RO water for drinking. If
you fill a two gal jug for the fridge it goes bad very quickly without
the chlorine. RO water needs to be fairly fresh for drinking. Which
is why people invest in the pressure system under the sink.


On 20 Feb 2004 13:06:09 -0800, concerned_RO_user
> wrote:

>Hi,
>
>I am preparing to get an under-sink RO system with pressurized storage tank for
>both drinking and aquarium use, and have a question about the auto shut-off
>(ASO) valves included in most systems.
>
>When the ASO valve is activated it shuts down the input to the RO cartridge and
>causes the pressure differential across the membrane to decrease (and maybe even
>reverse). If residual water remains in the cartridge, will this situation allow
>any significant amout of impurities to pass from the "dirty" side to the "clean"
>side of the membrane, especially at night when this condition would last for
>many hours?
>
>Would it be better to shut off the flow at the brine (dirty) output of the RO
>cartridge rather than the input? If so, are there any valves that would do this
>based on the pressure in the storage tank, just like the regular ASO does?
>
>Or am I making a mountain out of a molehill?
>
>Thanks for any info.


http://www.geocities.com/ctmidnite53/

[Michael Ross]

The issue you bring up is something that can happen after the shutoff
activates. You will get a SLIGHT blend of the water from the "dirty" side
of the R/O membrane. This blend may be very insignificant. One thing we
recommend that our customers do to guarantee the highest quality water
possible is to completely drain their resevoir tank once/month. This will
remove any lower quality water and replace it with brand new water.

When we test our customer's R/O systems, we drain their tanks before we test
it. This is to ensure that we are testing the water straight from the
module, instead of a possible blend water sitting in the tank.

--
Mike Ross
Culligan Rochester


"concerned_RO_user" > wrote in message
...
> Hi,
>
> I am preparing to get an under-sink RO system with pressurized storage
tank for
> both drinking and aquarium use, and have a question about the auto
shut-off
> (ASO) valves included in most systems.
>
> When the ASO valve is activated it shuts down the input to the RO
cartridge and
> causes the pressure differential across the membrane to decrease (and
maybe even
> reverse). If residual water remains in the cartridge, will this situation
allow
> any significant amout of impurities to pass from the "dirty" side to the
"clean"
> side of the membrane, especially at night when this condition would last
for
> many hours?
>
> Would it be better to shut off the flow at the brine (dirty) output of the
RO
> cartridge rather than the input? If so, are there any valves that would
do this
> based on the pressure in the storage tank, just like the regular ASO does?
>
> Or am I making a mountain out of a molehill?
>
> Thanks for any info.
>