Replacing RO membrane based on TDS readings

[RODI Qs]

I have a BRS RODI kit, the 6-stage water saver with a booster pump.

My inline TDS meter reads 23 tds on line 1 with the booster pump off, and around 8 tds on line 1 with the booster pump on.

Line 2 reads about 2-3 tds consistently, regardless of my booster pump being on or off.

Assuming 95% rejection rate, I'm trying to figure out if my RO membranes need replaced. I assume I need to considering 5% of 23 AND 5% of 8 are both smaller than 3? Is one reading better worth using than the other to determine this moving forward?

I'm also using their dual 75gpd "water-saver kit". Any thoughts on if this is actually the optimal setup while I'm shopping membranes?

 

[chipmunkofdoom2]

I'm not familiar with the line nomenclature you're using. Could you confirm where line 1 and line 2 are coming from as well as where they go?

 

[DesertReefT4r]

I think its time for new membranes even 8 ppm is getting up there imo. 23 ppm is nkt good for sure. Sounds like it time for new di resin as well.

 

[Buckeye Hydro Verified Sponsor]

Feel free to give us a call when you're in front of your system for help troubleshooting.

Russ
513-312-2343

 

[Buckeye Hydro Verified Sponsor]

My inline TDS meter reads 23 tds on line 1 with the booster pump off, and around 8 tds on line 1 with the booster pump on.

Line 2 reads about 2-3 tds consistently, regardless of my booster pump being on or off.

Assuming 95% rejection rate, I'm trying to figure out if my RO membranes need replaced. I assume I need to considering 5% of 23 AND 5% of 8 are both smaller than 3? Is one reading better worth using than the other to determine this moving forward?

I'm also using their dual 75gpd "water-saver kit". Any thoughts on if this is actually the optimal setup while I'm shopping membranes?

With an RODI system, you want to know TDS in at least THREE LOCATIONS:
1. Tap water
2. RO water (your 23)
3. DI water. (your 2 to 3)

The vendor you mentioned seems to configure systems with an inline meter with only TWO probes.

To calculate the rejection rate you need to compare the TDS of the Tap water to the TDS of the RO water. So... you don't have the information needed.

Russ