How many stages does RO unit need

[bgiles11]

I am getting ready to purchase a RO unit. And I was wondering is there any stage differences I should be concerned about.

[nyvp]

depends how bad the water in your area is. I went with a 5 stage

[bgiles11]

<a href=showthread.php?s=&postid=10152972#post10152972 target=_blank>Originally posted</a> by nyvp
depends how bad the water in your area is. I went with a 5 stage How do I find this out? test it with a TDS meter?

[Billybeau1]

Yes. For example, my tds is about 125. I use a 4 stage. Sediment, carbon, membrane and di. The di really gets it down to 0 tds. I only have to change my first 2 filters once every 6 months and the di once a year. The membranes last many years if the filters are kept up with.

[Buckeye Hydro]

<a href=showthread.php?s=&postid=10152400#post10152400 target=_blank>Originally posted</a> by bgiles11
I am getting ready to purchase a RO unit. And I was wondering is there any stage differences I should be concerned about.

A standard RO system configured for aquarium use will have 3 stages (in this order):
sediment filter
carbon block
RO membrane

A standard RO/DI system configured for aquarium use will have 4 stages (in this order):
sediment filter
carbon block
RO membrane
DI resin

Are there variations on this? Sure. All sorts. Multiple sediment filters, multiple carbon prefilters, multiple membranes, and multiple DI stages. But what I wrote above describes a standard system well.

Russ @ BFS

[powdertang05]

i have tds of 60 n my area and in my other home its 2000 ive used the purley h20 on both water systems and they brng me to less then 10 before the di everytime.

[Buckeye Hydro]

That's a 99.5% rejection rate at your house with tap water at 2000 ppm. Hmm... Did you mean to say it is 200 ppm?

[46bfinGA]

2000 ppm?What color is it,lol? Mine is around 25ppm at my house.

[KaniRyde]

What is a TDS meter and where do you get one?

[Buckeye Hydro]

TDS = Total Dissolved Solids. These meters measure in parts per million.

If you measure the TDS in tap water for instance, you get a very good estimate of the contaminants (things other than H2O) if the water. That's not the full story, but let's leave it at that for now.

One way to measure the performance of yor RO membrane and your DI resin is with a TDS meter. RO membranes are factory spec'ed to reject a certain percentage of tds in the feed water. So for instance, if your tap water had 100 ppm TDS, after your RO membrane you might measure between 2 and 10 ppm TDS. That is, the membrane rejected 90 to 98% of the TDS in the feed water.

Most in this hobby then rely on DI resin to take out the remaining TDS before the water is ready for use in the tank.

Since we are a sponsor I think I'm able to say that we carry TDS meters - 2 models of handhelds, 3 models of dual inline meters.

Russ @ BFS