# RO water system benefit/consumption



## dodidoki (Mar 21, 2012)

I bought one....I am disappointed. I build it as it is wrote in manufacture book. RO water cames drops by drops, unusual "side" water flows out continously....it will be VERY expensive!!!!


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## Ray (Mar 21, 2012)

That does not sound like it is performing correctly, but more details would be needed before that can be judged correctly.

A "standard" residential system, used at the conditions at which they are specified (65 psi [450 kPa], 77°F [25°C] incoming water pressure) should put out 3-4 units of flush water for each unit of pure water produced.

If the temperature is lower, the membrane will be more restricted, so less pure water will be produced, driving up the flush-to-pure ratio. This chart will show you the effects of changes in temperature and pressure.

Decreasing the incoming pressure also tends to increase that ratio, but not to the same degree.

What is the rated capacity of the system, and what size flow restrictor is on the flush water line? They are typically specified in ml/min.


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## eggshells (Mar 21, 2012)

So is it better to tap it in the hot water rather than cold water?


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## orcoholic (Mar 21, 2012)

I think it would be very expensive to tap into the hot as it would waste a lot of heated water.


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## eggshells (Mar 21, 2012)

yeah I was just looking at the chart. So I guess the best way is the colder the water. Increase water pressure.


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## keithrs (Mar 21, 2012)

Check your water pressure.... Make sure you have the restrictor on the right side going the right way.

Let it run for an hour or more.... I have mine outside and when it's cold out I get very little ro water while I wait for the incoming water to "warm" up my membrane.


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## Ray (Mar 21, 2012)

...and for folks interested in being more conservative, you can always increase the restriction on the outlet of the flush side of the membrane. Yes, it will mean the need to replace membranes more often, but if you pay for your water, and especially if you also pay a sewerage fee based upon water consumption, in a few calculations I've done for folks, it ends up being a significant savings anyway.

FWIW, I've been operating a custom-built 200 gpd system, and at design pressure and temperature, it should be a 1.14:1 ratio. In reality, due to the lower pressure and temperature of my GH water supply and the lower output, I measured the ratio coming out at 2.03:1. In almost 4 months, I see no degradation in the output, so the membrane is apparently not fouling very much.


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## eggshells (Mar 21, 2012)

By often.. Do you mean once a year. It says on mine 2-5 years to replace the membrane.


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## dodidoki (Mar 21, 2012)

PURE Pro M500. cca 1 litre/hour soft water versus 20 litres unusual water. Very disappointing.


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## Justin (Mar 21, 2012)

something is not right. the pure water should be coming out at the volume ratio like Ray said.


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## keithrs (Mar 21, 2012)

It's 50 GPD unit...... That's about 189 L per day. At that rate you should have a very fast drip to slow light stream....


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## Ray (Mar 21, 2012)

eggshells said:


> By often.. Do you mean once a year. It says on mine 2-5 years to replace the membrane.


The standard recommendation level for a system used at its capacity is:

Sediment filters - 6 months
Carbon prefilters - 12 months
Membranes and (if used) carbon postfilters - 24 months.

I'll admit that those are pretty conservative. As I don't produce at capacity, I run about 2x time periods those in my own system.


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## NYEric (Mar 22, 2012)

For a new unit at worst you should be running 6:1. Also, my unit says used cold water.


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## dodidoki (Mar 22, 2012)

I noticed that if I close the way of wasted water, RO water begins flow faster. I thought about: if I close the way of wasted water, preassure will increase backwards to the tap water side of membrane....so I can adjust the system with appropriate closure of wasted water to optimal running. Is it right?


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## keithrs (Mar 22, 2012)

You don't want to close the waste side off completely..... You can add a smaller restrictor but that won't necessarily give you more production.... Your limited by the membrane flow rate. 

I would recommend going to a higher GPD membrane with the appropriate restrictor for the ratio you want.


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## dodidoki (Mar 22, 2012)

keithrs said:


> You don't want to close the waste side off completely..... You can add a smaller restrictor but that won't necessarily give you more production.... Your limited by the membrane flow rate.
> 
> I would recommend going to a higher GPD membrane with the appropriate restrictor for the ratio you want.




No I didn't closed waste side completely, I adjust the system into that level, that RO water outflow is equal to wasted water outflow (1/1 ratio). My system can produce with this adjusment about 3 litres /hous RO water.


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## eggshells (Mar 22, 2012)

How about going 100gpd. What size is your holding tank?


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## Ray (Mar 22, 2012)

What size flow restrictor was provided with the system?


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## keithrs (Mar 22, 2012)

Do you know the TDS of your supply water? I ask because if it's high you'll foul the membrane fairly quickly at 1:1. If you're ok with knowing that then no worries.


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## NYEric (Mar 22, 2012)

Unless you pay for water, my taxes take care of that!, you can run 2:1 or 3:1. Plus if you dont have a lot of plants a couple of gallons on the side should do you for a day.


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## Stone (Mar 22, 2012)

NYEric said:


> Unless you pay for water, my taxes take care of that!, you can run 2:1 or 3:1. Plus if you dont have a lot of plants a couple of gallons on the side should do you for a day.



What? You don't pay for water??


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## NYEric (Mar 24, 2012)

Stone said:


> What? You don't pay for water??



Water is covered by taxes, gas and electric in coop maintenance!


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## dodidoki (Mar 24, 2012)

dodidoki said:


> I bought one....I am disappointed. I build it as it is wrote in manufacture book. RO water cames drops by drops, unusual "side" water flows out continously....it will be VERY expensive!!!!



Repairman said that osmotic membrane is wrong. It will be changed next week for free.....


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## likespaphs (Mar 24, 2012)




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## eggshells (Apr 5, 2012)

What is the biggest RO holding tank that I can get for a standard kitchen sink?


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## Ray (Apr 6, 2012)

eggshells said:


> What is the biggest RO holding tank that I can get for a standard kitchen sink?


Doesn't that depend upon how big the cabinet is under the sink?

Most residential systems are supplied with a 3.2-gallon tank, having about 3 gallons of capacity. As you get bigger, the air volume that pushes the bladder for water pressure takes up more room. A 20-gallon tank, for example, has a bit over 14 gallons of water capacity, and is about 30" x 16" diameter.

The biggest one I have seen is 120 gallons = 2' diameter by a bit over 6' tall, and costs $1000.

Most growers who use RO don't rely on a pressure tank, but store it in an open-air tank (far less expensive), and use a pump to deliver it for watering.

I have sold a half-dozen systems in the last month with no tank whatsoever, In some cases, the individuals plan to connect it to a spigot and turn on the water, filling milk jugs or the like, then turning it off again.


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## eggshells (Apr 6, 2012)

Thanks Ray, tha is exactly what I was looking for. I'll get a pump to match a pressure of tap water which is 65?


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## Ray (Apr 6, 2012)

I'd say go lower.

The pump I use cycles between 40-60 psi and at 60, you have to be careful not knock plants out of the pots.


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## Justin (Apr 6, 2012)

Ray said:


> I have sold a half-dozen systems in the last month with no tank whatsoever, In some cases, the individuals plan to connect it to a spigot and turn on the water, filling milk jugs or the like, then turning it off again.



That's how i use mine. For a small indoor collection, I have the R/O system connected to a kitchen faucet adapter and fill up milk jugs throughout the week. For a couple hundred plants/seedlings on lightstands, I use maybe 20 gallons per week.

I have been mixing 50% tapwater back into my R/O when i feed, for extra calcium, but flush with pure R/O every other watering. One thing about using R/O for Paphs, root growth is phenomenal.


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## eggshells (Apr 7, 2012)

Ray said:


> I'd say go lower.
> 
> The pump I use cycles between 40-60 psi and at 60, you have to be careful not knock plants out of the pots.



Hi Ray. What is a good submersible pump that can dispense a 5 gallon bucket water slowly and with not a lot of pressure but at least a good flow. I bought an eco 396 pump and attached to a garden hose. Im wondering if the eco 633 is better.


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## cnycharles (Apr 9, 2012)

eggshells said:


> Hi Ray. What is a good submersible pump that can dispense a 5 gallon bucket water slowly and with not a lot of pressure but at least a good flow. I bought an eco 396 pump and attached to a garden hose. Im wondering if the eco 633 is better.



I use aquarium power heads to pump out of and into five gallon buckets. You can get small and large ones, either pumps that are expected to pump deep under water or sit on top of a water column to circulate in the tank (power head). plugs into a normal outlet, uses cheap tubing, you can pinch the tubes to close down the water and open to let more flow out. never too much pressure with one of these, though they don't pump up high but if I need to water a top shelf in my cart, I just set the 5 gallon bucket on a cheap bar stool. you can't put a garden hose on an aquarium/pond pump, but you really don't need one


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## Ray (Apr 10, 2012)

I don't know that I can make any specific recommendations. I carry some Hydrofarm submersibles that might do the trick - I mostly sell them to folks building terrariums - and can certainly get you anything they carry, if you're interested in something bigger.


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## keithrs (Apr 10, 2012)

I use a little giant 5 msp pump.... It pumps at about 30 psi and has great flow....


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## eggshells (Apr 10, 2012)

Thanks guys. I bought a coiled garden hose and a eco 396 pump. It works but on only one setting "center". Would have been nice if I can use all the setting. I feel that I need a bigger pump but for now It seems to work.


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## T. migratoris (Apr 10, 2012)

I filter water into a small basin that sits under the GH benches. I use a Shurflo 8005-733-255 110V diaphragm pump to draw water from the basin & deliver it through a combination of 1/2" pvc and 3/8" reinforced hose (could be pvc also) to a stainless steel watering wand. The pump has an integral pressure switch that regulates pressure between about 40 & 60 psi (at the pump) but at the end of the wand, after passing through piping & tubing, the pressure's much lower and it's perfect for watering. I paid $88 for the pump. I've been using the system for a couple of years now without any glitches.


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