Replacing my RODI Membrane - 100gpd to 150gpd

[Jake Martensen]

Good evening! I have a 6 stage RODI unit. I run 1 sediment filter, 1 x 5 micron carbon filter, 1 x 1 micron carbon filter, 1 container of Cation, 1 container of Antion and 1 container of mixed bed resin. I previously had 100 GPD membranes in it. I ordered and installed 150 GPD membranes in it on accident (didn't read close enough).
Question: What is the downfall of making this change?
Will it burn through Resin and carbon blocks faster?
I have a 400g system and typically do 50g water changes every 2 weeks. I generally don't keep more than 80 gallons of fresh water on hand.
Thanks!!!

 

[EeyoreIsMySpiritAnimal]

@Buckeye Hydro should be able to help

 

[Buckeye Hydro Verified Sponsor]

Good evening! I have a 6 stage RODI unit. I run 1 sediment filter, 1 x 5 micron carbon filter, 1 x 1 micron carbon filter, 1 container of Cation, 1 container of Antion and 1 container of mixed bed resin. I previously had 100 GPD membranes in it. I ordered and installed 150 GPD membranes in it on accident (didn't read close enough).
Question: What is the downfall of making this change?
Will it burn through Resin and carbon blocks faster?
I have a 400g system and typically do 50g water changes every 2 weeks. I generally don't keep more than 80 gallons of fresh water on hand.
Thanks!!!

There are a bunch of issues wrapped up together here. In no particular order:

Unless you have naturally soft, or softened water, you should not be using two (in this case 150 gpd ) membranes plumbed in series with a flow restrictor designed for a single 100 gpd membrane. You'll be replacing membranes often.

What flow restrictor are you using?

What is your feedwater Total Hardness?

150 gpd membranes typically do not have a rejection rate as good as lower gpd membranes. So that will result in higher TDS permeate and shorter resin life.

150 gpd membranes are typically spec'ed at 60 psi or 65 psi depending upon the brand. What pressure are you feeding them?

Is there some reason you need to produce RODI water so fast?

Do you have the system set up such that it won't short cycle?

 

[Buckeye Hydro Verified Sponsor]

Good evening! I have a 6 stage RODI unit. I run 1 sediment filter, 1 x 5 micron carbon filter, 1 x 1 micron carbon filter, 1 container of Cation, 1 container of Antion and 1 container of mixed bed resin. I previously had 100 GPD membranes in it. I ordered and installed 150 GPD membranes in it on accident (didn't read close enough).
Question: What is the downfall of making this change?
Will it burn through Resin and carbon blocks faster?
I have a 400g system and typically do 50g water changes every 2 weeks. I generally don't keep more than 80 gallons of fresh water on hand.
Thanks!!!

double post

 

[five.five-six]

IMO, it’s always best practice to use the slowest membrane you need. They tend to hit their target rejection rate better. I do have a 100GPD but when it goes I’ll prolly revert to a 30 GPD. I use makeup water of about 15G about once a week and I keep a 32 gal brute trash can filled or being filled at all times. When I draw my 15 gal of makeup water, I don’t need anymore for a week so what’s the point of 100GPD? When I do a30 gal WC the brute is filled the next day. What’s the point of having a 150 GPD? In my case?

 

[Jake Martensen]

There are a bunch of issues wrapped up together here. In no particular order:

Unless you have naturally soft, or softened water, you should not be using two (in this case 150 gpd ) membranes plumbed in series with a flow restrictor designed for a single 100 gpd membrane. You'll be replacing membranes often.

What flow restrictor are you using?

What is your feedwater Total Hardness?

150 gpd membranes typically do not have a rejection rate as good as lower gpd membranes. So that will result in higher TDS permeate and shorter resin life.

150 gpd membranes are typically spec'ed at 60 psi or 65 psi depending upon the brand. What pressure are you feeding them?

Is there some reason you need to produce RODI water so fast?

Do you have the system set up such that it won't short cycle?

Thank you for the feedback. I will replace the 150s with 75s. The restrictor I have on it is a 550 which is rated for the 75 - 200 GPD.
Don't know the hardness of the incoming water but my TDS reads 195 coming in and 0 going out but the phosphates are still testing high.
I will replace the membranes and let you know how it works out.

 

[Buckeye Hydro Verified Sponsor]

The restrictor I have on it is a 550 which is rated for the 75 - 200 GPD.

A 550 ml/min flow restrictor is intended to produce about a 4:1 ratio of concentrate to permeate with a 50 gpd membrane.