RO/DI Membrane question

[infamoustrini]

Hello, I got a RODI setup and was told its 75gpd , there is a flow restriction on the line with "1000" on it. I tried researching and found this flow restriction is good for 100gpd?
Please let me know if to purchase a 100gpd or 75gpd membrane. Also, what brand membranes are best?
thanks

 

[Buckeye Hydro]

Assuming you have factory spec conditions, that flow restrictor is not a good match for a 75 gpd membrane. The real test is to measure your waste water production and compare it to your purified water production - you want about a 4 to 1 ratio. Depending upon your water temperature and pressure, you'll probably find you are producing much more waste water than needed (e.g., 6 to 1, or 8 to 1). Let us know if you need help with an easy way to measure the ratio.

It is much cheaper to replace the flow restrictor (~$4) than to replace the membrane.

As for the best brand: Filmtec.

Russ

 

[infamoustrini]

Thank u. Well i have to buy a new membrane so i can get the 100gpd membrane?

 

[Buckeye Hydro]

Assuming you get a Filmtec 100 gpd, and you have 50+ psi, and 77F water, the 1000 flow restrictor will give you a 4:1.

Russ

 

[infamoustrini]

Ok thanks should injust get a 75gpd membrane and leave the 1000 restriction or do i have to change the restriction if i get the lower membrane?

 

[Buckeye Hydro]

You can run either a 75 or a 100 with that flow restrictor. But...

Most people want to "tune" the amount of waste water to produce about a 4:1 ratio. It's unlikely a 75 with that flow restrictor will produce a 4:1, unless you have high pressure and warm water.

So if you want to stick with a 75, you'll want to get a different flow restrictor.