ready for DI?

my tds from the RO is 20-25 tds.

so im guessing that im ready to start using the DI resin?

and sorry for so many of these threads all the sudden, but noone i know can set these up, so im asking you all. thanks for stikkin with me!

 

that's way better! RO is working... I would think it should come down more than 90% rejection rate, though. I know I mentioned this before, Are you using the correct flow restrictor?

 

not sure what a flow restrictor is...

ill go test again, its still running.

 

the flow restrictor is built into the waste water output of the RO. It should match the GPD of the membrane you put in your housing.

Does the GPD of your new membrane match the GPD of the old one? Or did you upgrade to a higher GPD with the new one?

you can and should change the flow restrictor to make it work correctly if it does not match the GPD of the membrane you have.

see here:
http://www.spectrapure.com/St_replac_p3.htm

 

I take it you are breaking in or flushing a new RO membrane?

You need to flush 3 to 5 gallons of water through the membrane before attempting to install the DI.
It sounds to me like you need to do more flushing if it is a Dow Filmtec 75 GPD RO membrane which should be 96-98% efficient when broken it or seasoned. With 20 to 25 still coming out that would mean your tap water TDS is quite high to begin with or the membrane is not flushed or both.

If its a Dow Filmtec 100 GPD which I hope like heck it is not as they are the worst possible membrane you could buy since it is not a RO at all but really a 90% efficient/rejection rate nano filter not reverse osmosis. It will eat DI resin like crazy.

What is your tap water TDS ? Say it is around the national average of 250 that would mean you are only 90 to 92% rejection or removal efficiency at this point. Flush some more and keep checking the TDS until you are at least 96% rejection.

Tap water TDS-RO only TDS, divided by the tap water TDS, x 100 gives you the rejection rate or removal efficiency. Example, 250 tap-20 RO TDS = 230, 230/250=.92, 092x100= 92% removal.

 

18 and steady. im gonna hook it up to DI now.

starting tds of well water, unfiltered: 345
RO: 18
DI: better be zero lol

 

im not sure on the membrane, it just came with the filter and was the exact same one as the used one. its a second hand purchase from someone i do trust so i think its fine.

 

yeah, but unless you know that the GPD matches the flow restrictor, it may never produce water the way it was designed. I would try to find out if I were you.

 

just read your post. my calculations are that im at 95 percent rejection rate right now.

 

ok. ill look for the old membrane.