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#1
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Reverse Osmosis Question...
Hi All,
This is a simple tech question regarding a Reverse Osmosis System.... Recently I've purchased such a system of 100GPD. At the beginning the output was really 100GPD, but now it works with 85GPD even after I've replaced the Filters. (One Pre and two carbon filters....) I can add that the water quality is great and I use the system quite often. Is this a normal decrease in such systems ? Thanks, A.B |
#2
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Reverse Osmosis Question...
RO units will vary in output with the amount of impurities in your
water. I have a 50 gpd unit and only get 15-18 gpd. You can use a pump to force the water through the membranes which would double or triple your output. -- Mark http://www.cichliddomain.com "gizmo" wrote in message ... Hi All, This is a simple tech question regarding a Reverse Osmosis System.... Recently I've purchased such a system of 100GPD. At the beginning the output was really 100GPD, but now it works with 85GPD even after I've replaced the Filters. (One Pre and two carbon filters....) I can add that the water quality is great and I use the system quite often. Is this a normal decrease in such systems ? Thanks, A.B |
#3
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Reverse Osmosis Question...
Water pressure sometimes dictates how efficient these systems will work.
In my old house, the water pressure was so strong, my RO unit was something like 20% more efficient (that is - it produced 20% more water). When we moved, the water pressure (going into the house) was lesser, thus the unit produced less water. cheers, Boris "gizmo" wrote in message ... Hi All, This is a simple tech question regarding a Reverse Osmosis System.... Recently I've purchased such a system of 100GPD. At the beginning the output was really 100GPD, but now it works with 85GPD even after I've replaced the Filters. (One Pre and two carbon filters....) I can add that the water quality is great and I use the system quite often. Is this a normal decrease in such systems ? Thanks, A.B |
#4
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Reverse Osmosis Question...
"Boris" wrote in message le.rogers.com... Water pressure sometimes dictates how efficient these systems will work. SNIP With that in mind.....certain filtration devices work better with slower, steady pressure....especially bio devices.....also.....slower water flow allows more O2 to be introduced into the water on external filter systems.....just my .02 Sneaks |
#5
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Reverse Osmosis Question...
Thanks (I do feel a bit better....)
But isn't it a bit frustrating waiting like ages to get a decent amount of water ??? I've never seen any note about this phenomena in the vendor manuals.... But I guess I'll have to live with it.... "rmc" wrote in message ... RO units will vary in output with the amount of impurities in your water. I have a 50 gpd unit and only get 15-18 gpd. You can use a pump to force the water through the membranes which would double or triple your output. -- Mark http://www.cichliddomain.com "gizmo" wrote in message ... Hi All, This is a simple tech question regarding a Reverse Osmosis System.... Recently I've purchased such a system of 100GPD. At the beginning the output was really 100GPD, but now it works with 85GPD even after I've replaced the Filters. (One Pre and two carbon filters....) I can add that the water quality is great and I use the system quite often. Is this a normal decrease in such systems ? Thanks, A.B |
#6
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Reverse Osmosis Question...
Quote:
The amount of water you get from your membrane depends mainly on three things, pressure, temperature and fouling. The 100 gpd rating of your membrane is actually based on your feed water being 25 degrees centrigrade and 50 psi. By increasing the pressure you increase the output (by doubling the pressure you would actually be able to double the output to 200 gpd), however as temperature goes down so does the output therefore you will produce more water in the summer months than the winter months. Another factor that effects membrane performance (and the problem that is most likely effecting you) is membrane fouling. If you have a hard water supply you will get limescale deposits on your membrane, the more your membrane is fouled the less water it will produce. Limescale is not the only foulant membranes are also very prone to biological fouling. The first thing to try to eleviate this is to "flush" your membrane, you can do this by simlpy removing the restrictor on your reject. Without the restrictor there is no back pressure on your membrane and therefore reverse osmosis does not take place, instead of some of the water passing through the membrane all the water is forced over the surface of the membrane this will remove any foulants (assuming the membrane is not too fouled). After a few minutes replace your restrictor. Your unit should now be producing more water. If there is no improvement it may be that the membrane is too fouled for flushing alone to be effective. On an industrial unit chemicals would be used to clean the membrane, on a small domestic system this just isn't feasible. From the sounds of things though your membrane is only has a 15% fouling factor, so if the flush does not work non the less continue to flush the membrane from time to time to stop the fouling getting worse. Another thing to concider is that your membrane is only designed to be run at 15% efficiecy (i.e. 15% good water to 85% reject), if you run it any higher the membrane will over recover and foul more quickly. If you wish to have some facts and figures on your membrane you may find it of interest to look at the data sheet for the FilmTec TW30-1812-100 (http://www.dow.com/webapps/lit/litor...2.pdf&pdf=true), whilst yours may not be a FilmTec it will give you a good idea of just what you can get out of your membrane. I hope this has been of sosme intersest to you. |
#7
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Reverse Osmosis Question...
"gizmo" wrote in message
... Hi All, This is a simple tech question regarding a Reverse Osmosis System.... Recently I've purchased such a system of 100GPD. At the beginning the output was really 100GPD, but now it works with 85GPD even after I've replaced the Filters. (One Pre and two carbon filters....) I can add that the water quality is great and I use the system quite often. Is this a normal decrease in such systems ? Thanks, A.B There are many factors that determine the amount of product water produced by a RO unit. The rating of GPD is based upon fixed values of the variables. Its rare to get the actual rating.... The purpose of the sediment filter is to keep the carbon block filter from clogging. The purpose of the carbon block filter is to keep chlorine from getting to the TFC membrane. Water temperature, water pressure, and TDS are key factors affecting product water rate. Here is a link to some manuals for Spectrapure that give formulas and tables for rate production: http://www.spectrapure.com/support_p0.htm Its a good investment to add a membrane flushing valve and loop to your RO unit. Its also a good idea to tune your unit's capillary flow restrictor to your conditions to ensure your waste to product ratio is appropriate. You definitely need a chlorine test kit to signal when to change the carbon block filter. |
#8
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Reverse Osmosis Question...
"Sneaks" wrote in message et... "Boris" wrote in message le.rogers.com... Water pressure sometimes dictates how efficient these systems will work. SNIP With that in mind.....certain filtration devices work better with slower, steady pressure....especially bio devices Could you explain or provide an example of the statement below? .....also.....slower water flow allows more O2 to be introduced into the water on external filter systems.....just my .02 thanks! NetMax Sneaks |
#9
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Reverse Osmosis Question...
Well there is a point here regarding the O2 specially when filters are
replaced and O2 enters the system hence will effect the output... BUT..... shouldn't take too long and the O2 is out of the system..... In any case the effects are minor.... "NetMax" wrote in message . .. "Sneaks" wrote in message et... "Boris" wrote in message le.rogers.com... Water pressure sometimes dictates how efficient these systems will work. SNIP With that in mind.....certain filtration devices work better with slower, steady pressure....especially bio devices Could you explain or provide an example of the statement below? .....also.....slower water flow allows more O2 to be introduced into the water on external filter systems.....just my .02 thanks! NetMax Sneaks |
#10
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Reverse Osmosis Question...
"gizmo" wrote in message ... Hi All, This is a simple tech question regarding a Reverse Osmosis System.... Recently I've purchased such a system of 100GPD. At the beginning the output was really 100GPD, but now it works with 85GPD even after I've replaced the Filters. (One Pre and two carbon filters....) I can add that the water quality is great and I use the system quite often. Is this a normal decrease in such systems ? Thanks, A.B a decrease in output is normal. Unbelievable the amount of water they waste though. I installed a T fitting on mine with a valve that allows me to shut off the waste water going to the sink drain and redirecting it to a line I put into the basement and then into large plastic garbage cans. I use the waste water for all my water changes on my 30+ tanks. Rick |
#11
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Reverse Osmosis Question...
Hi All,
This is a simple tech question regarding a Reverse Osmosis System.... Recently I've purchased such a system of 100GPD. At the beginning the output was really 100GPD, but now it works with 85GPD even after I've replaced the Filters. (One Pre and two carbon filters....) I can add that the water quality is great and I use the system quite often. Is this a normal decrease in such systems ? I remember reading in a recent copy of PFK that RO units are given their daily usage fisgures under careful environmental control such as pressure, 3 bar and water temp 76F. Most people do not have water that temp from the tap and I don't think I have 3 bar pressure. All this makes a difference to the output. Regards Mark |
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