Odd RO/DI issue...

[RokleM]

I have a AirWaterIce Typhoon III that is about three years old now. I purchased it before I knew about BuckeyeFieldSupply, but have ordered all my filters from there ever since.

1 micron sediment
Matrikx® CTO/2 (Workhorse)
Matrikx® 1 Chlorine Guzzler
75 GPD Filmtech
Color changing DI

~300 TDS at the tap
Normally 80 PSI (booster) at the membrane

Long story short, my current membrane was pushing two years (first one only lasted a year becuase I accidentally turned on hot water once) and I burned through the last batch of DI pretty quickly. I ran a quick RO only check, and was hitting 50 TDS after. I wasn't overly surprised, becuase I've made a LOT of water with this membrane (26k gallons at least through the unit), so I ordered a new 75GPD RO, all new filters again, etc.

Removing all the filters, I put 1/4 cup of bleach in the first chamber, ran it through, thoroughly washed/rinsed, etc. I reassembled everything ran 5-10 gallons of water through, then started testing.

80 PSI at RO
~300 TDS at the tap
800 flow restrictor (tested a 550, but didn't honestly see a huge change)
~50 TDS after RO
~0 after DI
1/3 ratio

37 PSI at RO (no booster)
~300 TDS at the tap
800 flow restrictor (tested a 550, but didn't honestly see a huge change)
~35 after RO
~0 after DI
1/4 ratio

So I'm confused. Yes, it will work, but I'll burn through DI like crazy. I'm getting the same results as my last membrane which I thought was going bad. I KNOW for a fact this unit use to get ~12 TDS after RO. I'm almost positive something has happened in the last 3-6 months that has changed my efficiency, but I don't know what it could be other than colder water.

I've reseated the membrane three times (tried pushing it firmly, tried barely inserting and allowing the lid to push in). Flushed the membrane for 5+ minutes. I took apart the sediment and two carbon chambers to ensure there was a mark on the filter/gasket (showing pressure and not bypass). I took off the autoshutoff which I don't use. It was already bleached/cleaned.

I've hung around Russ from BuckeyeFS, AZDesertRat, and a number of the other guru's in here to be dangerous although I don't proclaim myself as a genius in this area. I'm out of ideas. Anyone have an idea on next steps?

[tkeracer619]

Have you contact Buckeye? Sometimes a bad membrane slips through. I agree something isn't right with those numbers.

[RokleM]

Not yet, but it seems odd that the new one would have almost exact same numbers as the last one I thought was dying.

I was going to give Buckeye a buzz next week (if he doesn't see it over the weekend).

[Buckeye Hydro]

You are getting lower TDS out of your membrane at lower pressure - that's the opposite of what you should be seeing: higher pressure should yield higher rejection.

I don't know how you are getting your tds readings. Are you confident the readings are correct?

[RokleM]

I was using an inline for rough guesses, but did verify with a PEN. I will double check again tomorrow ensuring I'm using a 100% clean container and pen only. Very odd and had me stumped. I'll probably run it a good 30-45 minutes before any testing just to be 100% sure as well.

[Buckeye Hydro]

OK - don't turn it off the get the sample - keep in running and just stick your sample container under the flow to get a sample...

[RokleM]

Confirmed via pen (think it's HM TDS3), except my tap TDS jumped considerably today (tap to output TDS ratio stayed the same). I'm assuming it's all the runoff and gunk from the snow/rain/sleet. I flushed the membrane for 5+ minutes and produced 2+ gallons of water before testing the output.

500 tap (pen, clean glass rinsed w/ 0 TDS RO/DI)
80 PSI
800 flow restrictor
90 TDS after RO (pen, clean glass rinsed w/ 0 TDS RO/DI)
0 TDS after DI

I even went and ripped out the RO flush, auto shutoff, and all unnecessary parts. It's literally input, sediment, carbon, carbon, RO input, RO output / waste output, glass / sink. Same results.

The only thing I can think of is something went wacky with my RO membrane canister. Is this even possible? Is there a way that too much unfiltered water can be sneaking into the "processed" tube?

I can supply some pictures if it helps, but I don't think there is much to see.

What's the rejection on that 24 GPD home system Russ? @35 PSI, my output from bladder/faucet is 16 TDS at 350 TDI tap (96%, sounds good to me). That uses the same faucet to feed the system as my reef system (literally unplug drinking from the faucet and plug in reef).

[Buckeye Hydro]

That yields an 82% rejection which is way too low. Yes - you can get waste water out of the permeate port if the membrane isn't fully seated or if the cup into which the RO membrane seats is cracked.

Check your waste to permeate ratio - it will look like you don't have enough waste water if you have some waste water sneaking out the permeate port.

The rejection onthe 24 gpd membrane is the same as on the 50 and 75 gpd - 96 to 98%.

Not sure if I understand what you mean, but you are not running DI water through your bladder tank and faucet, right?

[RokleM]

It's running at 3/1. I may try an adjustable flow restrictor and be done with it. I don't know if I can pick up one of those locally, so I might order that. I inspected the membrane and housing, but didn't see anything irregular. It's cheap enough I might replace that too, becuase I'm grasping at what could possibly be wrong with no real changes in the system other than swapping filters for two years.

On the 24 gpd, bladder, etc. No, I'm running it exactly as you sent it, completely separate from my reef RO/DI. I was using it as simple verification, that the system was working correctly at the correct rejection rate and that my handheld pen was working. Merely just a double check on my part. Everything is perfect there, which is what I expected.

[Buckeye Hydro]

If you have 3 parts waste and 1 part permeate, sounds like your membrane is seated and the housing is not cracked.

When you sanitized the system did you have the RO membrane removed from the housing?

[RokleM]

Yes, all filters, the membrane, and DI were out of the system. I scrubbed the unit with some soap and hot water, reassembled, and inserted the bleach into the first chamber. I turned the faucet on slowly, filling the chambers in order, and opened all 3 exits (RO, DI, and waste). I then shut the water off and let it sit 5-10. I then flushed it for a good 10 minutes with water flowing out of all exits again prior to disassembling and installing the filters/membrane.

[Buckeye Hydro]

Eric - you have the luxury of having two systems. You could do a test where you swap membranes and restrictors and that should let you know if its the membrane or another part of the system that is causing the trouble.

When you check the TDS on your RO system - do it before the water gets to the tank. The tank water TDS will be higher than straight RO water TDS.

Russ

[RokleM]

Ahh, very good idea Russ. I'll give that a try tonight.

[RokleM]

Thanks Russ, I think I figured it out. It's actually the RO chamber itself. I have NO clue how this could happen, so let me tell you what I did.

I put the 75 RO in the drinking water and was getting very low TDS (as expected). At that point I fiddled around with a few other ideas, then decided to put the 75 membrane and membrane chamber from my drinking on the reef system. 17 TDS output :eek1: So somehow the chamber itself is bad, how the membrane is sitting in there, or something. I reseated it probably a half dozen times as I've fiddled trying to fix things, so I don't think it's the actual seating in the chamber, but the chamber itself.

Over pressurized somehow? Stressed the plastic and bloated? The Air-Water-Ice RO chamber that's bad on this unit doesn't seem to be near as solid as the one on the drinking system from you.

None the less... Good news it's fixed... Bad news is I have to do yet another parts order :lol: Your assistance is VERY much appreciated.

[Buckeye Hydro]

Glad you found the problem.

We actually did quite a bit of shopping around to find the membrane bousings we use - they are certainly not the least expensive out there, but they are "stout" as you saw, and we've had very good luck with them.

Russ