replaced ro/di filters/resin now can't get below 2 TDS

jcw

New member
My unit is a puratek 100gpd deluxe 4 stage RO/DI with booster pump. It had been running for more than 2 years with the same filters, resin. 0 tds coming out of the DI. 90 at the tap, 0 after RO.

Recently I was getting a lot of TDS creep after RO when the unit turned on after the autoflush completed. Goes up to 40's then back down to 0. Then the TDS went never dropped below 2 after the RO. The filters were getting very discolored so I changed everything out.

Went with BRS. Spoke with someone and specifically mentioned my unit and said I would like to get the best replacement filters to match the performance I got with the original.

I went with the Filmtec 75 with the restrictor. Replaced them per the video instructions at the site.

Now, I get 90 going in, 8-9 out the RO.

Any reason this should be happening? I thought moving from the 100gpd membrane with 90% rejection rate to the 75gpd with 98% rejection rate I should be getting less TDS.
 
I see you have a booster pump, what is water pressure after your pump and into your filter?
 
Similar experience here and I'm running the 100gpd.
http://www.reefcentral.com/forums/showthread.php?t=2216732

What resin were they referring to? the DI resin? It seems to me the TDS of the RO is high which is even before the DI resin is encountered.

The stock unit's membrane is GE's TFM-100. I specifically asked if people have had problems with the filmtec 75gpd membrane on my type of system which I described in detail (with the booster pump).
 
I think the membrane needs some time to break in. I know when I when I replaced my membrane with a filmtec its performance steadily increased over the first 50 or so gallons.
 
On dow's website the pdf...

"¢ It is recommended that systems using these elements rinse the elements for 24 hours, prior to first use, to meet NSF/ANSI 58 Standard.
"¢ The first full tank of permeate must be discarded. Do not use this initial permeate for drinking water or food preparation.


the absolute pressure rating is 150psi, so I'm well within the range.

I have run it about 3 hours and the tds seems to be improving a little.
 
Good to hear. Mine started out around 35 and is not about 12. My tap water is around 400
 
i have always uesed and am on lake michigan water like you my house is at 60psi
my tds is about 175-200 from the tap depending on time of year and my ro output tds ranges 10-20 the di takes it down to zero. have you cleaned the contacts on your tds meters, maybe when you backflushed it they got dirty.
 
I set up two RO/DI at two houses about 1 mile from each other. Mine and my cousin's.

His tap TDS is 144.

Mine is 90.

I changed the membrane at the same time with the same dow filmtec.
His unit does not have the booster pump. PSI about 50.
Mine has a booster pump. PSI as stated above is 75-80.

His RO output after about a week is 4. 140/144=97%
Mine isn't getting any better at 9-10. 80/90=88%

I think I have a bad membrane...



Two things I might have done wrong.
I was told that the DI resin did better refrigerated if not used right away. so I put both the resin and membrane in the refrigerator. (not freezer).

The second thing is when I changed out the carbon block, I ran it through the membrane instead of flushing it for a while.

I wish this was made clearer with the replacement filter kits...
 
I rechecked things using a handheld TDS meter. The same one I use at my cousin's house.

My TDS is 140 from tap.
10 after RO.

for a rejection rate of 130/140= 92.8%. Not bad but not as advertised.

Maybe my inline TDS meters are not well calibrated for higher tds???
 
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