RO/DI decision time

well I let it run for 10 minutes and was getting 30-29 tds, according to buckeye, it is a 75 GPD Dow FilmTec membrane. my inline is conected:

in- after the carbon blocks, before the membrane
out- after the membrane, before anything else

I think I am going to run through my resin fairly quickley at this rate
 
Yes, you will run through your DI quickly. I'm sorry I don't really know what is wrong. If you truly are getting 94% rejection then you are under spec for the DOW filmtec. I guess at this point, once you've exhausted your other possible options, I would try to contact Buckeye or Dow and see if there is anyway to exchange the membrane as a defective one. It would be nice too if you could confirm your tds readings with someone else's meter. Do you have any local reefers with a hand held unit that you could borrow? You just want to really make sure that it's the membrane before claiming it defective. Try that next. Try to get someone's hand held meter to make sure the readings are consistent. You can still try to contact Russ at buckeye in the mean time.
 
10 TDS would be 98% rejection
15 TDS would be 97% rejection
21 TDS would be 96% rejection

So the average rejection for these membranes is listed as 98% but anything above 96% is within the manufacturers minimum rejection rate. Do you recall what you water pressure is too? That can impact your rejection rate as well. I'm glad you verified your TDS meter, that's one less variable to worry about.
 
I have 2 gauges, 1 before the carbon blocks reads 70 pounds and the one after them reads over 60 pounds but it changes, stays around 65
 
Dow does not guarantee the efficiency of their membranes, they can be +/- 15 or 20% according to them.
There is only one place that tests and guarantees membranes and that is Spectrapure. Also unlike any other manufacturer/vendor/supplier EVERY membrane that leaves their facility is a wet membrane in a special proprietary pickling solution that improves efficiency. They do not sell dry membranes. Their Select series membranes go a step above that are hand tested and guaranteed to be 98+% rejection rate. No one else offers this service or the guarantee.
 
Your pressure is fine and so would not be the problem. Sometimes the RO membrane is not perfectly sealed within it's housing and you can get some mixture of waste and permeate, thus causing an increase in tds. Typically though, that results in very high TDS permeate and a very low rejection rate. I kind of doubt that's what's happening but if you wanted to give it a shot, you could try re-lubing and re-seating the membrane. Use 100% silicon grease like you would use on an o-ring. It's a long shot but what the heck. After that I think you have nothing to lose by contacting Buckeye and seeing if he has any tips or if there is anything he can do for you. I would also still try emailing or calling DOW. You never know, they may be able to help you out. It's always worth a shot.
 
I may just blow $100 on a SpectraSelect, I have enough hobbys and do not want to start water as a new one :p at this rate, by the time I have made 100 gallons, my DI will be almost 1/2 done
 
Well, that's a very good route to take. I don't have a spectrapure unit but I do use their membrane and I'm a little over 99% rejection. Seeing as how you have great prefiltration and good pressure, if should give you the results you are looking for. Let us know how it turns out.
 
ok, so on the SpectraSelectâ"žÂ¢ membranes, is there a difference in the rejection rates on the 40, 60 and 90 GPD units?
 
If you have two DI canisters get the MaxCap and SilicaBuster cartridges. If you have a single DI get the SilicaBuster as the MaxCap is not designed to be a standalone DI cartridge, it works best as a roughing or primary DI if you will.
They do not sell bulk resin for either as their resins are all custom hand blended in house. They do not sell any off the shelf resins.
 
Scrap the granular catalytic carbon and GAC, go to a 0.5 or 0.2 micron prefilter, a single Matrix Chlorine Guzzler in the 0.5 or 0.6 micron range and move the empty canister to the final DI position. A Chlorine Guzzler will do a better job and last longer than the granular media will. The Matrix blocks have much greater pore area than any granular media.
Granular media is hell on a membrane since it breaks down and create fines which can plug a membrane. Colloidal material and carbon dust are tough to flush out.
 
I just bought the system.. last week and you are telling me I need to spend $150 to fix it

this is exactly why I sat in the sleet and driveing rain with quarters and bottles all those years
 
All you really need is the spectra select membrane. I would wait 6 months (when you need to change out your prefilters anyways) and then order prefilters and DI resin from twopartsolution and a spectraselect membrane from spectrapure. Twopartsolution.com sells bulk .5 um carbon blocks and they will suit you fine. The spectra di resin is great but you don't need to spend the money on that yet. Adding their membrane alone will make your DI resin last for seemingly ever. I go through a single replacement DI cartridge per year because I get 2 tds out of the spectra membrane. I have virtually the same input water as you since I am just a bit further south in SoCal. Here is what I would do and in the order I would do it.

1. Contact Buckeye and tell them you were hoping for a better rejection rate. See what they say. If they send you a new membrane and it's not what you were hoping for then get the spectra membrane later.

2. Contact Dow and see if they can do anything for you.

3. In six months when you order new prefilters, just get two .5um carbon blocks and install those instead of GAC. The carbon blocks will be about the exact same price so this won't cost you anymore. You can even buy them in bulk at twopartsolution.com . You can also buy DI resin from them in bulk.

4. At this time, if you still aren't happy with your membrane you can order the spectra select one. This will really be the only expense that we couldn't really predict.

You do not NEED to reconfigure your unit. It was just a recommendation but you will be fine with it just how it's configured. Also, to conserve carbon blocks you can simply rotate the 3rd stage one to stage 2, throw out the stage 2 cartridge, and put a new block in stage three. This will give you more than enough protection against chloramines and still only have you purchasing a single carbon block every six months. The new membrane (and DI resin you may use this 6 month period) is the only unforeseen expense. Sorry that happened. It's particularly disappointing because you live in a high TDS area.
 
Buckeye uses good prefilters and the 0.6 micron Matrix carbon block in most of their systems so I would imagine you have those already.
How are you testing the TDS? Are you giving the TDS creep time to pass before taking a sample and making sure the meter and glass or sampling container are triple rinsed in DI between each reading?

And there is absolutely no need for multiple carbon blocks or CGAC if you use a good block. Don't worry about all the swapping back and forth, just use a good one to begin with.
 
I have an update and a question.

UPDATE:
I have been making water for about three hours now and the meter shows the membrane input at 292ppm and the membrane out at 3ppm. If I'm doing the math right, that's 98.9 rejection. I would recommend the 150 GPD membrane.

QUESTION:
Can I assume that if I have a 0 TDS that there is no chlorine in the water? I don't have a chlorine tester. I'm using the default 10,5,1 filters.
 
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