Need ro/di help - Tds not quite right

R

RLS

[Greetings All,

I bought a 5-stage RO/DI unit in anitcipation of setting up a reef aquarium about 1.5 years ago. Well...due to certian monetary and wife related issues, the unit sat idle for a year. Anyway...I've been using the unit since I set up my system about four months ago, but only recently bought a TDS meter. I tested the RO/DI water and got a reading of 100 TDS , while my tap water is reading about 150 TDS. My unit is from AirWaterIce and has the quick flush and DI bypass options. The DI resin still has color and and I don't think the micron or charcoal filters go bad. What is the deal? As I understand it, I should be getting readings in the single digits. My understanding is that the quick flush valve is open at he "-" position and closed at the "I" position, and the DI bypass is on at the "I" position and off at the "-" position. Am I doing something wrong, or do I need to replace my filters?

Thanks,
Robert]
 
[OK. for starters; with the flush valve closed,
1) is the 100tds reading with di bypass off? (ie; RO/DI water is output)
2) what is tds reading with di bypass on? (ie; just RO water output) ?]
 
[Don't know if you still have your directions, but you need to have both in the closed postion (believe it is what you refer to as the "I" position) to get RO/DI water out. Also, I heard that if you let your filters dry out, then they are no longer good. I do not know this for a fact though. Also, the general rule is to replace the sediment and carbon filters once a year.

Just go out to airwaterice.com and contact Walter. He will be more than happy to answer your questions since it is a unit from him. If you don't have your directions anymore, then I would be more than happy to look anything up for you you (I have the Typhoon III, which is a 5 stage filter also).]
 
[Thanks for the replys. I have been running it the the DI bypass valve in the open position. I was thinking that it was bypassing the last (DI) chamber when it was closed. I will test the output with the bypass valve in the closed position. The directions don't discuss the bypass. I e-mailed Walter when I started to use the unit and he indicated that as long as the DI resin still had color, it should by OK. Would RO water still be at around 100ppm? I thought it should by lower. Does 150ppm sound right for tap water?]
 
[Sounds about right for tap. RO should indeed be in single digits. In fact I never see mine go over about 4ppm unless I need to change filters.

I agree that if you just had it sitting the filters should be fine. Were they in extreme heat or anything? I'm grasping at straws at this point!]
 
[Are you sure the TDS meter is calibrated? Use it to test some distilled water. Distilled water shoud read zero as long as it was not made using a copper distillery.

You did not answer the question about the RO membrane drying out, if it did, it is most likely bad.

Like Keith, just grasping at straws.]
 
[I'm not sure if the RO membrane dried out. The unit was stored indoors, so it was not subject to extreme heat of cold. I callibrated the TDS meter with 800 ppm solution. I am going to by some more solution and recalibrate. I guess I may need a new membrane.]
 
[When the unit was stored, was it in the original package (this would be OK because they are shipped sealed, clean and wet), left inside the membrane housing with or without water (with water it might be OK but could have bacteria issues, without most likely bad) or removed and placed in a zip lock bag with water, frozen? I have read in the past the best way to store a membrane is wet in a sealed bag in the freezer. The idea of freezing is to avoid any type of bacteria growing in the membrane from the standing water. I know this may all be water under the bridge but just in case anyone else reads the post they might be able to use the info later.]



Edited By SALT on 1092418896
 
[Stanley is correct. If you have a used unit and you store it, you'll have issues later. You should dispose of all the filters, and I have heard that you can freeze the membrane to protect it. The better option is to hook it up somewhere and run it once a week, just to make a few gallons.]
 
[Thanks everyone for your replies. The unit was stored new, but the membrane must have dried out. I will be ordering a new set of filters. Does anyone know where to get them locally for a reasonable price? AirWaterIce sells the 75 gpd filmtec for around $45. I think the carbon and sediment run around $10 each, with the DI at around $25.]
 
[I find the AirWaterIce filter prices to be very reasonable (at least when I ordered a little while back compared to other places). The RO filter will be your most expensive. Also, I know AirWaterIce has the good carbon filters. Someone who knows can chime in here, but there are a couple types of carbon filters (ie. carbon block, coconut, etc.) and some really are not good to use.]
 
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