Short life of RO and DI

[allsps40]

Ok I just got a DI a few months back with color changing resin. The resin is just starting to change color at the bottom and my TDS as gone from 0 to 3. My RO membrane is also a few months old when it was new I got 8 TDS now I am getting 26 TDS. Pressures are good, it is getting time to replace the carbon and pre filters. What the heck?! Oh membrane is a Spectrpure.

[sporto0]

Do you have a flush kit for the membrane? Flushing the membrane once a week will greatly increase the longevity. DI resin on the other hand will not last that long depending on the rejection rate of your membrane, also, sediment cartridge & carbon block all help to remove solids & organics, so they work in conjunction with one another. How many GPD is the membrane rated for?

[allsps40]

90 gpd. I got over a year out of my last membrane, same one.

[zigzag1]

A couple of things that can help DI life are to not run the unit in short bursts with frequent cycling on/off, but in large 'batches' of production. Also, don't run your first 5-10 minutes of RO product water through the DI, as it will have a higher TDS. I use the water produced in the first few minutes for other things, like rinsing of GFO, GAC, etc. GL!

[sporto0]

Sounds normal to me, the rejection rate should be about 10%, so if your tap water is say 300 TDS, then water from your membrane would read 30 TDS & then DI removes the rest, it's always 6 of one or half dozen of the other when it comes to RO units, your either replacing resin or membranes. One thing of note, next time buy a 75 gpd membrane, they only reject 2% so your DI resin lasts longer, but you will have more waste water because it takes longer to make the same amount as 100 gpd, see what I mean?

[KStatefan]

Contact Spectrapure.

Your 90 gpd membrane should be at least 97% Rejection. What is your waste water to good water ratio. It should be 4:1. If it is to low the membrane will go bad quickly.

[moliken]

just personally, i'd say you have gotten 'reconstituted' di. i change 3 gals every day and evaporate 1 and am on my 3rd month of the same di. so that's 120gpmonth X2.5 months. going into di is at most 160 tds, then after a few minutes it's down to 15 or so, but always 0 exiting di. it's used up about 1/2 of the di

[doctorgori]

I see the OP lives in Arizona....(PHX?)
....doesn't fully explain it but having lived there I know you won't get the same mileage compared to Great Lakes water or elsewhere in some cases... I know in Maricopa cty TDS is ridiculous and the pH is near 7.9ish in parts of the valley

BTW isn't Spectrapure local in Tempe?; somewhere off University between McClintock & Rural ? I'd talk to the guy as suggested, he's a pretty nice person

[allsps40]

No I dont have a flush kit. Tap water TDS is over 500. Rejection rate is 4-1. I normally make 10-15g at a time.