RO or RO/DI

[kirby]

just wondering if i can use just an RO system i live in new york city if that matters

[AZDesertRat]

RO/DI. RO by itself only does 90-98% of the job, its the DI that does the final polishing. NY has low TDS but extremely high TSS or suspended solids in many locals since they do not treat much of their water in conventional treatment plants. This is being remedied now but plants are not scheduled to come on line for some time yet. The problem is consistency, with tap you do not have that, with RO/DI its the same every time.

[kirby]

so what would happen if i opt out on the di part because i have a friend that has a good deal on just a ro unit made by spectra pure...thanks

RO/DI. RO by itself only does 90-98% of the job, its the DI that does the final polishing. NY has low TDS but extremely high TSS or suspended solids in many locals since they do not treat much of their water in conventional treatment plants. This is being remedied now but plants are not scheduled to come on line for some time yet. The problem is consistency, with tap you do not have that, with RO/DI its the same every time.

[AZDesertRat]

You can always add a DI to an RO system.

Do you know the condition and history of the unit he is selling? Often used units end up costing as much or more than new ones when you discover they need new replacement filters and a membrane. Do you know the TDS of the tap water and the RO only water so you can confirm the rejection rate? Not to disuade you but used units usually are not the way to go even if it is a brand name like Spectrapure, which is all I use by the way.

They have RO/DI systems, add on DI filter kits and replacement filters all on sale here to give you an idea of costs:

http://www.spectrapure.com/email/customer-...eciation.html#1

 

A brand new ProPlus at $149 might be less expensive since it includes a full size DI, inline TDS meter and pressure gauge all in the base cost. Adding a DI to an existing unit plus replacing filters and possibly a membrane if you do not know its condition amy end up being moreexpensive.

[kirby]

I will have to ask him but i thought 50 bucks was gonna be a steal...maybe i will just stick with buying a new one instead and not have to worry about that stuff haha

[AZDesertRat]

At a minimum find out how old the unit is, when the filters were last replaced, how old is the membrane, what is the TDS coming out and going in and when was it last disinfected. You might also want to get a TDS meter and pressure gauge if it does not come with them.

As you can see the cost of even a prefilter, carbon block, TDS meter, pressure gauge and add on DI added to the initial $50 may exceed the cost of a new ProPlus with a warranty. You have to weigh the cost youself as $50 isn't a bad deal if the unit is in good shape, is working at 96-98% rejection still and does not need filters right away.

[kirby]

thanks for all your help