i just installed a new filmtec 75gpd membrane along with a new flow restrictor for 75gpd and been having probs getting the tds down. i have 711 tds from tap (galveston, tx) with 69 tds after the ro membrane. the restrictor is one of those inline restrictors so i'm not sure if its accurate or not. my old membrane was a 100gpd tfc membrane i got off of ebay and got tds down to 20. i tried reseating the new membrane and seems to not improve it at all. anything else anyone can think of that i might have missed?
ro help
- Thread starter bboytius
- Start date
AZDesertRat
In Memoriam
How long have you let it run. It can take 5 gallons or more to clean the membrane and break it in. What are you using to test with and waht are you using for a container to test in? Let it run, use a very squeaky clean drinking water glass with no dish soap residue or water spots on it to sample in and make sure your TDS meter is rinsed in DI after each use to keep it clean.
What is your waste ratio, is it somewhere cloes to 4:1, measure it with a measuring cup or other graduated container and a watch, don't guess at it.
What is your waste ratio, is it somewhere cloes to 4:1, measure it with a measuring cup or other graduated container and a watch, don't guess at it.
ermeate ratio. i only let it run for a couple of hours with the old restrictor, so i dont' know if that'll affect it or not.
just measured the waste to permeate ratio and got around 4:1. measured it by using a measuring cup and seeing how much water was produced in 1 min from the ro line and the waste line. also repeated measurements using 30 second interval and got the same thing. do you guys think it could be a defective membrane?
AZDesertRat
In Memoriam
Yes they do occasionally turn out bad membranes. I would return it for a replacement or my money back. If I might make a suggestion here, your tap water TDS is much like it is here in Phoenix, 700 or better. www.spectrapure.com has a hand tested Spectrapure Select 90 GPD membrane that is guaranteed to produce better than 98% rejection and I have found it is well worth the extra money. Mine is averaging 98.96% rejection. A 5% improvement in rejection rate will double the life of DI resin which will pay for the membrane in a hurry and considering a membrane should last 2 to 3 years or more it will end up saving you money in no time. Yesterday my tap water was running 750, my RO only was 7 and RO/DI is an honest less than 0, 18.2 megaohms to be exact.
Thefilterguys
.Registered Member
Any idea of what kind of water pressure you have and did you remove your old flow restrictor? 4:1 is the prefered waste ratio for a 75 GPD Filmtec membrane. Is it possible you have a bad auto shutoff valve try bypassing it and see if the TDS improves if you have one? Just dealt with this problem and the shutoff valve was malfunctioning causing the membrane to load up. Bypass the shutoff and flush the membrane for a few minutes and see if the TDS goes down to normal which in your case should be 14-16 ppm.
Jim
Jim
