Serious RO/DI question?

nikonosis

New member
I bought an rodi on ebay, one of the ones recommened on RC. The TDS was was 0ppm when I got it, around 8 months later the tds was up to 8ppm. I just bought new filters and installed them yesterday. I made some new water last night and I just tested the PPM in it tonight and it was 42ppm. I first thought that maybe the container somehow got something in it so I made a little cup of water and tested it. It read almost 300ppm??? WTH is going on?

These are the filters I bought.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=4436016977&rd=1&sspagename=STRK:MEWN:IT&rd=1

I didn't get a new RO membrane because I heard they last for a year but going from 8ppm to 42 to 300, something seems weird.
Can anyone help me out?
 

ScubaTC

New member
Are you on Middleburg water or well water? I wouldn't think your membrane has gone bad, but have no idea as to the name brand/quality.

Once, I had a membrane that was used for around 4 years. I did 45gal water changes each month and with the auto top-off it was replacing about 6-10gal a day in evap. That's a lot of use and during that time only had to maintain the replacement of my filters to keep the ppm as close to zero as possible.
 

ScubaTC

New member
Maybe you were shipped the wrong size micron filters? We usually try to stay with .5 to 1 micron. I know there are 5 microns out there and maybe even 10 on the sediment.

Just a thought.
 

Ikaria

New member
Talk to Reefkeeps, he should be at the meeting. I know he had that RO/DI, so could probably tell you more.
 

nikonosis

New member
<a href=showthread.php?s=&postid=6981263#post6981263 target=_blank>Originally posted</a> by ScubaTC
Are you on Middleburg water or well water? I wouldn't think your membrane has gone bad, but have no idea as to the name brand/quality.

Once, I had a membrane that was used for around 4 years. I did 45gal water changes each month and with the auto top-off it was replacing about 6-10gal a day in evap. That's a lot of use and during that time only had to maintain the replacement of my filters to keep the ppm as close to zero as possible.

its running on well water.
 

nikonosis

New member
<a href=showthread.php?s=&postid=6981472#post6981472 target=_blank>Originally posted</a> by PelagicMagic
your tds meter could be busted. those things are cheap and need to be replaced often

i dunno. ill bring it with me tomorrow if i remember and have rob test it on his rodi water.
 

nikonosis

New member
<a href=showthread.php?s=&postid=6981386#post6981386 target=_blank>Originally posted</a> by ScubaTC
Maybe you were shipped the wrong size micron filters? We usually try to stay with .5 to 1 micron. I know there are 5 microns out there and maybe even 10 on the sediment.

Just a thought.

I don't think so, they look identical to my old ones except i got a clear di filter so i can tell when it goes bad.
 

raddogz

Premium Member
Did you test the first five or so gallons of ro/di water or did you test it afterwards?

When you replace the sediment, and carbon filters you let the system make about five gallons of ro/di water, but you can't use it. If you stick a tds meter in the water it will read some crazy number. The reasoning is that you have to flush that the "additives" for a better lack of words out.
 

ScubaTC

New member
Raddogz is right, I always let mine run for a good while after replacing the filters and the TDS reading is always higher and works it's way back down to zero.

Just a though.. do you still have you old filters. If you know they were running at 8ppm when you replaced them, maybe put them back in to see if your still getting that.... unless they have already hit the trash.
 

AZDesertRat

In Memoriam
Whomever recommended that unit to you did you a disservice. Its not a very good RO/DI. If your triubles continue look at a 75GPD Typhoon III from www.airwaterice.com, 75 GPD Premium series from www.buckeyefieldsupply.com, units from www.purelyh2o.com , www.thewaterguys.biz or www.melevsreef.com.
All use top notch components and filters including 75 GPD Dow Filmtec true RO membranes not imported Chinese knockoffs.
RO/DI is not a place to skimp as you have found out the hard way.
Notice the membrane you got does not mention a name and I have tried unsucessfully to contact them asking for a brand. Unfortunately you got what you paid for.
 

nikonosis

New member
<a href=showthread.php?s=&postid=6983892#post6983892 target=_blank>Originally posted</a> by AZDesertRat
Whomever recommended that unit to you did you a disservice. Its not a very good RO/DI. If your triubles continue look at a 75GPD Typhoon III from www.airwaterice.com, 75 GPD Premium series from www.buckeyefieldsupply.com, units from www.purelyh2o.com , www.thewaterguys.biz or www.melevsreef.com.
All use top notch components and filters including 75 GPD Dow Filmtec true RO membranes not imported Chinese knockoffs.
RO/DI is not a place to skimp as you have found out the hard way.
Notice the membrane you got does not mention a name and I have tried unsucessfully to contact them asking for a brand. Unfortunately you got what you paid for.

not really because the tds is going down. i just needed to run about 10g through the new filters. its under 20 now and ive only run about 6 gallons through it. I can buy any kind of membrane i want for the rodi because its made exactly like those expensive name brand ones you are talking about. the same guy that sold me the rodi also sells 75gpd membranes and when this one runs out i will probably get one.
 

BeanAnimal

Premium Member
1). Your membrane is a 100 GPD membrane. That means it is not a TRUE REVERSE OSMOSIS MEMBRANE.

2.) It only has a 90% rejection ratio

3.) It is designed to run at 60 PSI

4) Your DI cartridge is horizontal. This allows channeling and bypassing. A true vertical canister forces the water from the bottom up through the resin. This ensures that the water makes full contact and can not bypass the resin beads.

Call them "expensive units" or whatever your like. The person who recomended that garbage did you a disservice.

With such a high TDS input, you are using A LOT MORE resin than you should due to using the wrong membrane. You are wasting a LOT of water due to the fact that the membrane is designed to be used under higher pressure than household water nornally is. You are still getting HIGH TDS output because your horizontal resin cartridges are undersized and allow the water to channel and bypass.

If they do sell membranes that are NOT DOW FILMTEC made by DOW, then they are not selling good membranes. NOTE: Others use FILMTEC fabric but the membranes are still junk due to their poor construction.

You asked for help, you have all of the information that you need now.

Get a FILMTEC membrane and get a TRUE vertical RESIN canister. You will save yourself a lot fo money in the long run (short term with your TDS).

Bean
 

nikonosis

New member
<a href=showthread.php?s=&postid=6984163#post6984163 target=_blank>Originally posted</a> by BeanAnimal
1). Your membrane is a 100 GPD membrane. That means it is not a TRUE REVERSE OSMOSIS MEMBRANE.

2.) It only has a 90% rejection ratio

3.) It is designed to run at 60 PSI

4) Your DI cartridge is horizontal. This allows channeling and bypassing. A true vertical canister forces the water from the bottom up through the resin. This ensures that the water makes full contact and can not bypass the resin beads.

Call them "expensive units" or whatever your like. The person who recomended that garbage did you a disservice.

With such a high TDS input, you are using A LOT MORE resin than you should due to using the wrong membrane. You are wasting a LOT of water due to the fact that the membrane is designed to be used under higher pressure than household water nornally is. You are still getting HIGH TDS output because your horizontal resin cartridges are undersized and allow the water to channel and bypass.

If they do sell membranes that are NOT DOW FILMTEC made by DOW, then they are not selling good membranes. NOTE: Others use FILMTEC fabric but the membranes are still junk due to their poor construction.

You asked for help, you have all of the information that you need now.

Get a FILMTEC membrane and get a TRUE vertical RESIN canister. You will save yourself a lot fo money in the long run (short term with your TDS).

Bean

I said at the beginning of this thread that i was getting 0 ppm for the first 6 months and then it went up to 8ppm around 8 months. I figured i needed a new di so i just bought all new filters other than the membrane. BTW I can move my di to any position i want. It doesn't have to be horrizontal.

2.) It only has a 90% rejection ratio
emoves 98% to 99.99% of all chemical and harmful dissolved elements and 99% of all bacteria

3.) It is designed to run at 60 PSI
Actually its designed to be run at 45psi.

Tons and tons of people on RC recommend ebay RO+DI units and none of them have had problems with them that I have seen.
 

crumbletop

New member
I don't know where you are getting your numbers. From the link you gave in the OP, they provide a reference range that is 93% (300 ppm in, 20 ppm out). These numbers don't add up to 99%, much less 99.99%. The rejection rate has to do with the RO membrane ONLY, not what comes out after the DI. The whole point of the RO is to reject as much "gunk" as possible to save the DI resin. If you get a RO membrane that lets more stuff through, then you'll get less milage out of your DI resin. The DI is the part that needs replacing most often, and thus maintenance costs will be higher...

Also, one other point that might help you out, the system that you link to contains a GAC filter AFTER the DI to improve taste. Do you have that hooked up? It is probably adding stuff back into your water.

Whew, the grammar on those linked pages is horrid :) -- By their own advertising, you are getting "High technology to deliver the greatest quality water you deserve." Here's hoping your karma isn't all that bad ;)

Jack
 

BeanAnimal

Premium Member
Look you asked for help, and several people have shown you the facts. Choose to listen or choose to ignore, it is your money.

I don't care how many people recomended that unit, it is junk.

You can "turn the resin" any direction you like, it will not fix the inherent design flaw.

Your getting an output of 8 TDS when you should be getting an output of 0 tds!!! Either you are to stubborn to listen or you don't want help.

Your RO MEMBRANE is designed to work at 60-70 PSI, not 45. At 45 PSI the waste to clean water ration increases by a substantial amount and the membrane will not "self flush" as efficiently. This means shorter membrane life.

Did you ask a question to get answers, or to hear yourself talk? Sorry to be rude, but you have done nothing be refute the correct replies with bad information.

Bean
 
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