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MikeP

Reverse Osmosis Unit

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Hi

Here in the South East there has been little rain for close to two months and my supply is dwindling fast....down to around 10 days supply now......(unheard of in May - this usually only happens in August) and I am considering buying a Reverse osmosis unit. Does anyone use one and if so can they reccommend a brand? A google search turns up several but its hard to judge betweem them.

Thanks

Mike

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Iv'e just bought myself an RO-MAN but I would reccomend you take a look at osmotics http://www.osmotics.co.uk/ or RO-MAN http://www.ro-man.com/

Osmotics are really helpfull and i wish id got mine from them, they are particually popular with the reef people and have their own forum section:

http://www.ultimatereef.net/forums/forumdisplay.php?f=520

Edited by JimsPlants

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Got mine off eBay, from seller aquasafe-de. They regularly have them on auctions, as well as buy now. So, I added a weeks worth of their auctions to my watch list and bid on a quiet day. I got a three stage RO unit for £22 that way and it works great. If you buy an RO unit which you don't intend having permanently plumbed in then consider buying push-fit taps for all three connections (inlet, outlet and drain - usually 1/4", but check) as the RO membrane should never be allowed to dry out.

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Hi Mike

Similar to Mobile I bought a four stage RO unit from purityfilters on Ebay, it cost ninety odd quid but gives 125 US gall per day, which is a good quantity and spread over the life of the membrane and resin, probably works out at .004pence per gallon (excluding water cost if you are metered) so is a bargain in those terms.

In the recent hot weather it has proved invaluable providing water having a TDS of 1. I mounted it on a fence next to my water barrel to discharge the RO water into it, plumbed it in to a hose pipe from the garden tap, with the fittings provided and hey presto CP water. The waste water outlet I coupled to some more hose and use it to water the garden, it has a high mineral content but I don’t think the veg and flowers mind, it looks ugly but works.

I would recommend buying one if you can, just for the peace of mind.

Cheers

Steve

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Got mine off eBay, from seller aquasafe-de. They regularly have them on auctions, as well as buy now. So, I added a weeks worth of their auctions to my watch list and bid on a quiet day. I got a three stage RO unit for £22 that way and it works great. If you buy an RO unit which you don't intend having permanently plumbed in then consider buying push-fit taps for all three connections (inlet, outlet and drain - usually 1/4", but check) as the RO membrane should never be allowed to dry out.

I agree with all this and use the 3 tap method myself. Just remember to turn off the outlets before the water inlet to prevent the membrane drying out and keep the pressure up in the unit. If you plumb it in indoors you can fit a Y connector to the normal washing machine feed so it's not necessary to cut your cold water supply pipe. I know RO-man can provide all these bits.

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Thanks everyone for the advice.

Unit and accessories ordered from RO-Man....that should guarantee a month of rain now for sure......

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Thanks everyone for the advice.

Unit and accessories ordered from RO-Man....that should guarantee a month of rain now for sure......

What unit did you go for?

Of course it will rain now, it hadn't rained for months then the night after i order mine it chucks it down and i now have months worth of rain water stored and a brand new RO unit with no use for it :clapping:.

At least i know how to break a drought now.

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I went for the 50 gal per day unit with a DI filter.

Annoyingly it turned up without the 3/4" male adaptor needed to conenct it to the end of a hose so it took until yesterday lunchtime to get it up and running.....

Seems quite slow but 24 hours later I do now have around thirty gallons in the first waterbutt. Oh yes and it did rain at around 5:30 this morning.......only 3mm in the rain gauge so noting to get excited about.

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The RO membrane permeate rate is temperature dependant and is quoted at water temperature of 25°C. The reason for this is because water gets thicker the colder it gets. The permeate rate can be calculated, for example, if the water temperature was 15°C then the permeate rate would be approximately 36 gal/day on a 50 gal/day unit.

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Thanks Mobile that makes perfect sense. I thought the rate would go up over night when the water pressure increased slightly but it didn't seem to make much difference. I wonder what the temperature of mains water is? Not twenty five degress ever I would have thought. Still 30 gallons a day will suit me fine.

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The permeate will decrease/increase by approximately 3%/°F. Decreasing with temperature fall and increasing with rise. I was in charge of specifying and having installed a small scale industrial de-ionised water system in my last job, so picked up loads of useful/less information :biggrin:

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well after weeks and weeks of haveing no rain and my 5 butts so low that i,ve had to order one today from ro-man.

i want for the 75gallon 4 stage unit with di fillter.

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At least if you have ordered or got one installed, you have peace of mind and water when you need it, I may have some sort of syndrome but if I see my barells below half full I satrt to get twitchy and start the RO system going.

I see the wether forecast for the SE of the UK still doesnt show much rain coming. The members down there must be pulling their hair out.

Cheers

Steve

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I see the wether forecast for the SE of the UK still doesnt show much rain coming. The members down there must be pulling their hair out.

We are Outdoor bogs are almost dry I just can't spare the water for them, and now I hear we are in for a long dry hot summer :ohmy: where I am in Braintree in Essex we honestly have had nothing but a few drizzles since february and when I say drizzles I mean it didn't even wet the whole floor and evaporated soon after and didn't notice a difference in the water butts.

Have to say it's a big worry now.

Edited by mattybadboy44

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Hi Jim

I would attach an image if I understood the process......

Mike

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Hi Jim

I would attach an image if I understood the process......

Mike

You could upload it to a picture hosting site, such as http://tinypic.com/.

On TinyPic:

  • 'Browse...' for the 'File:'
  • 'Resize:' it, I recommend 640x480
  • 'Upload Now'
  • Enter the code
  • Copy the 'IMG Code for Forums & Message Boards' and paste it straight into your forum post.

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Like this?

1zwheyv.jpg

Yes that seems to work thanks.

I also bought a TDS mter to check its performance. Our tap water gave a reading of 245 and the water produced by the unit gave 4 for one water butt and 1 for the second so I guess its working.

Typically its now pissing down in South London.....

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Hi MikeP,

Yes, that's correct, except you missed off the [/img] on the end. You probably just missed that bit when you did a copy from TinyPic. I've correct it now, so you can see the picture in the post, without having to click on a link.

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Thanks for putting pics up, looks just like mine although the pressure guage is connected differently, did you put it on with the T-joint yourself?

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No thats where it was connected when it arrived.

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Typically its now pissing down in South London.....

Yes, I connected up my emergency unit - £100 of membranes and cartridges - and then it chucked it down all day

Now got to find out how to store a membrane without it rotting

Dave

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I've never had any problems with RO membranes rotting but I know that some aquarists store them wet in the fridge, i.e. in a sealed bag containing some RO water (maybe wrapped in clingfilm prior to putting them in the sealed bag?).

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I am seriously thinking about buying an RO unit in the near future but have a couple of questions....

Do you have to plumb them into the mains water or can you use a hosepipe or some other means of water supply?

I've read somewhere (on this forum?) that they produce a lot of waste water, approximately how much waste water per litre of RO water?

I was thinking of using it as a standby in case I run out of rainwater, but if it can produce all the water I need, that's two waterbarrels I can use for other plants.

Thanks for any replies, and sorry if the questions seem daft :flag_of_truce:

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Do you have to plumb them into the mains water or can you use a hosepipe or some other means of water supply?

You can get adaptors for connecting them to hose bib taps.

I've read somewhere (on this forum?) that they produce a lot of waste water, approximately how much waste water per litre of RO water?

This is true, they waste a lot of water. Typically, if it is uses a flow restrictor, there is between a 3:1 and 6:1 reject rate, with 4:1 being quite common, i.e. for every 1 part pure water produced, 4 parts are rejected. The reject rate is also dependant on pressure and temperature, with higher values of both being more efficient, but you're unlikely to get below 3:1 without using booster pumps and secondary membranes. Dependant on the quality of the feed water, pressure, temperature and required product water, the reject ratio could be 10:1. The reject water can be used for purposes that do not require pure water, bearing in mind that it will contain the contaminates that the RO membrane has rejected.

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