[simbo]

 Can somebody please advise o upgrading my 75g per day ro from ro-man. I have spoken to them and been told that i can buy a 100g per day upgrade kit and also add another 100 membrane,giving a 200g per day, but wanted to know if i could add another and make 300.
can i do this, the only thing i think i will also need is another membrane housing for the third membrane but could not find one on their site
its time to expand this wf thing
cheers simbo

[freshwater]

Simbo,

If you tap water flow and pressure can cope you can add up to 6 membranes.

steve@freshwatersystems.co.uk

[Sunshine Cleaning]

What pressure do you need to maintain?

[MNWC]

Cant you just buy say a 200gal membrane and put it in the original housing ?

[freshwater]

Bear,

you need a min of 40psi but 60-70psi is better.

Macus,

If you could get a 200GPD membrane then yes, but the biggest 12" membrane is 150GP. You will also need to change the drain restrictor to suit your new membrane.

steve@freshwatersystems.co.uk

[Sunshine Cleaning]

I dont understand the drain restrictor bit. I know i have one on a 200gpd unit. If as you suggest to marcus the membrane is replaced with 2 150's what drain restrictor would i need, or, would i do as you suggest in another post and get a needle valve?

[freshwater]

Yes you can use a needle valve to control the flow to waste.

The general rule of thumb is 10ml per min per gpd of membrane at 70psi. So a 100GPD should run to drains at a rate on a bout 1 litre per min.

With a needle valve you can adjust this up or down. As you reduce the water to drain your production rate goes up, but your TDS also goes up, and contra for if increas the the drain.

steve@freshwatersystems.co.uk

[simbo]

I am lost now!!

[freshwater]

Simbo,

When and if you buy a new membrane, who ever its from, ask for the correct drain restrictor, its as simple as that. If you are buying an add on membrane with a housing again ask for the correct restrictor. If (as it seems) you dont know a lot about ROs then dont bother with needle valves, just stick the easy route.

steve@freshwatersystems.co.uk