Hi, just purchased my first RO system with DI, it's a 250 GPD, I have just rigged it up & am a little disappointed with the flow rate, it has taken 20 minutes to create 5 litres of water, can anyone advise please on what I can do to increase the amount being supplied, I currently do not have any way to test my water pressure but it's certainly not a slow trickle!
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RO Question
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doug atkinson
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250 ! That's an odd size membrane. Where did you get it from
doug atkinson
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Just seen the listing and another sales gimmick stating not the correct facts. Unfortunately you get sellers that will say one thing then when you look at the specification totally different. My advise speak to who you bought it from. If it does not work return it back
Bumblebee72
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Listen to Doug, he's the man who knows what he's talking about :2_thumbs_up_-_animated:
I am listening to Doug, but would still like to know what this unit should be producing in an hour?
doug atkinson
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At correct psi etc 39 litres per hour so in 20 minutes 13 litres so double what your getting. Now if I'm correct if it is the same listing stating our membranes give you 20 % extra capacity at 50 psi. You just have to work the maths out and is false . If that is the listing. But if your membranes were 60 psi then at your performance your pressure going in would be around 10 psi . What is your ppm coming out!
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We keep saying that when it comes needing wfp window cleaning equipment, you have to deal with the main suppliers. Yes, they are more expensive but they are supplying product fit for the purpose of window cleaning.
Morning Doug, yes you have the correct listing, that is the correct RO I purchased, the ppm is coming out is "0" but the waste water seems to have a better flow rate than the pure, is this normal?
Spruce, you have a good point there! Yes I did purchase re the good price, but if I can prove the figures they have supplied are incorrect, I have a case to have this problem sorted
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You need to set that up if possible. Depending on the hardness of your water it could be anywhere between equal amounts of waste to pure and 3 parts waste to 1 part pure.
Some suppliers fit a tap to the waste water line which is also called the flush valve. When you open it fully 99% of the water will go through the membranes to waste. As you close the tap you restrict the water going to waste which puts pressure on the membranes to produce pure water.
You must never switch that valve off as some water must go to waste all the time you are making pure water.
Our water is reasonably soft and our r/o is set up with a pure to waste ratio of 1 to 1.
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The problem with quoted membrane performance figures is that they are like miles per gallon figures manufacturers give for the new cars they sell - impossible to achieve in everyday life.
R/o figures are over a 24 hour period - that's a day. They are also based on US gallons which are smaller that UK gallons (4 liters rather than 4.5 liters.) They are tested at a pressure far higher than we get at the tap and the water will be warmed to the most ideal temperature. The content of the incoming mineral composition of water is also strictly monitored so the membrane works at its optimum but doesn't have to work too hard.
These are impossible to achieve in everyday life. In our experience at home in our garage with our water pressure we could expect about a 1/3rd of their claims in summer (when the water is warmer) and less in winter when the incoming water is colder.
We have a big variation in water pressure in our town just 500 yds apart.
The important figures you need to identify your membrane efficiency (how well your membrane is working) is the tap tds and the tds of the pure water as it leaves the membrane before di. No matter what the pure tds is, the resin in the di vessel will polish it (or remove it) off. But the higher the tds the quicker you will go through your resin.
The first r/o we had was a 225gpd unit with 3 x 75gpd membranes. That was very slow and only just managed to direct fill a 375 liter tank I had on my trailer overnight (3pm till 7am the following morning.) We upgraded those membranes to 150GPD and bought a 1000liter IBC tank to process water into that. We used that for 6 years and it supplied 2 of us with planning.
4 years ago I replaced that with a 4040 and now don't have to worry about water at all. The r/o switches automatically on when water is drawn from the IBC tank and switches off when full.
You might manage with your r/o but you need a storage tank to process water into so your r/o can be working when you are out cleaning.
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The waste valve must never be closed fully when processing water. The r/o membranes should be removing up to 98% of those impurities, ie 235ppm leaving you with 5ppm for your resin to polish off to 0ppm. So you need the waste running to 'flush' those extra 235ppm of minerals away. If you don't they will clog up the membrane making it unserviceable.
With 240ppm you could try a waste to pure ratio of 1 to 1 but I would probably say you are better off with a slightly higher waste ratio.
Without going into too much detail, you need to balance the cost of extra water if you are on a water meter to the cost of replacement membranes. So restricting the waste a little will impact on the longevity of the membranes a little, but it doesn't make sense spending £200 extra on water to save £120 on membranes, if you understand my reasoning.
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doug atkinson
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If you take out the membrane and check the label you should have a part code and manufacturer. From that you can can do a search to see if it is rated at 50 psi. The point that is false advertising is saying 20% extra performance.
Even if the membrane is 50 psi and you match this against 60 psi membrane with pressure at 50 psi you will not get extra 20% yield. Challenge him on that and ask for the data
I have a reply from the seller:
Hi, the test production is feed water at 25 degree centigrade and 65 PSI pressure. Your test is for 20 min producing 5 liters that is 15 liters in on hour and 360 liters in 24 hours. I suggest to run the unit for 24 hours and see how much produces. Thanks
Hi, the test production is feed water at 25 degree centigrade and 65 PSI pressure. Your test is for 20 min producing 5 liters that is 15 liters in on hour and 360 liters in 24 hours. I suggest to run the unit for 24 hours and see how much produces. Thanks
doug atkinson
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If he is saying the test is at 65psi then if you measured his membranes against two brands of membranes rated at 60 psi the performance would all be the same. So to make claim 20 % more production is false advertising.
doug atkinson
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Spec is 70 psi rejection rate 95% made in Taiwan. Description on Ebay no way matches this.
An Axeon membrane is 60 psi 98 % rejection rate.
You get what you pay for but unfortunately there are a lot of unscrupulous sellers making loads of money.
An Axeon membrane is 60 psi 98 % rejection rate.
You get what you pay for but unfortunately there are a lot of unscrupulous sellers making loads of money.
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I concur.
I would go one step further and add another upgrade kit of housing, piping, john guest t pieces. I would also upgrade the membranes to 150gpd.
A 450gpd will give you ample water for 1 cleaner but you will need to process water into a storage tank, ie an 1000 liter IBC tank.
These r/o units work well but they are slow.
Had I known what I know now after many years of struggling with slow water production, I would go to a 4021 or even a 4040. If you don't have enough water you can't grow your business. I found it very frustrating when I ran out of water and there was still a few working hours left in the day. Just upgrading membranes and adding an IBC storage tank made the world of difference.
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