RO Membrane - Huntsville water

[H@rry]

I have been burning through RO membranes at a very fast pace lately. Has anyone else noticed that? Has our water quality in south Huntsville changed for the worse over the past year or so? I keep a log of when I change membranes and the last three were 7/12, 12/12, and 5/13. I notice the problem when it starts burning through DI resin at a much faster pace. I tested mine yesterday and it needed to be replaced so I ordered another one. I use FilmTec 100 membranes. I figured the last one gave up after about 400 gallons.

I change the .5 micron (not 5 micron) sediment filter and carbon block filter every 6 months.

Could there be something wrong with the RO housing that would cause this. Now that I think about it, it seems to have gotten worse after I added the flush valve. I flush it for 5 - 15 minutes every morning. I might be doing more harm than good since all that flush water has to go through the prefilters and may be exhausting the carbon.

Any thoughts?

 

[ChrisKey]

I noticed a large difference in my TDS when we moved up here 2 months ago to the North East side of Huntsville, but I don't know if it is due to water quality or some issue with the move that could have unpacked my DI Resin. I just ordered a flush kit in hopes that it will help with my output from my RO membrane. My Output from the RO Membrane (bought 2 months ago) is about 22 TDS and the output from the DI Resin is 16 TDS, so it is higher than I would like.

I also installed the FilmTec Membrane in mine when I upgraded to a dual 75gpd membrane setup (150gpd total).

 

[pickupman66]

harry, what is your TDS going into the membrane? if it is sky high, then yea it could be the culprit. I dont think anything under 300 would be that bad though. I have also had better luck at the 75 GPD membranes though from BRS. if you need mroe water, run a pair of those into a single DI resin chamber. also, you may want to check your Waste ratio. 4:1 waste: good should be the sweet spot.

Chris,

sounds like you need to change. that is SUPER HIGH coming out of there. My tap tds is 120 or so. I get 1 or 2 tds out of my membrane then 0 out of the DI.

 

[H@rry]

My unit does not have a digital meter for me to know the exact TDS value. It has a button for a green light / red light test coming out of the first DI chamber. That lets me know when to change the DI resin. I can take the DI cartridge out and put the empty canister on, change some dip switches in the test unit and use it to test the RO membrane. I don't know a number but I know it is not acceptable.

 

[Buckeye Field Supply]

What evidence do you have that tells you the membranes are going bad?

Russ

 

[ChrisKey]

I am hoping it is just false reading on the TDS meter, so I will install my flush kit and my BRS refillable DI Resin container with fresh resin to see if it makes a difference. I was getting 2 -3 TDS abotu two weeks ago.

But it is good to keep an eye on if we are using the same RO membrane and seeing a problem with short lifespans.

 

[Buckeye Field Supply]

To tell how the membrane is working, you need two TDS readings: 1)tap water, and 2) RO water (not DI).

Russ

 

[H@rry]

What evidence do you have that tells you the membranes are going bad?

Russ

See previous post.

 

[Buckeye Field Supply]

Harry - w/o the RO water and tap water TDS numbers you are flying blind in terms of understanding how your membrane is working. A pressure gauge and a TDS meter are really the minimum tools you'll need to troubleshoot your RODI.

Russ

 

[Chameleon]

In Bham the TDS is very low in the tap, around 110-115 usually. Harry, I'd recommend getting the spectrapure tested membranes as they are guaranteed 98% rejection. That means if your water is anything like mine you will be getting below 5 TDS coming off the RO and DI will last a long time.

I would first check to make sure your RO housing isnt leaking the brine water past the membrane anywhere. if this is the case your DI will be used up really fast.

On another note you can get a handheld HM (good company) TDS meter for 15 bucks or so shipped on Ebay.

One more thing, the 75GPD membranes I believe are a lot better in general than the 100GPD at overall rejection rate. If you could get by with a bit less production maybe switch your membrane and restrictor line to 75gpd filmtec (spectrapure calls the 75GPD a 90GPD, but they are the same membranes)

 

[Buckeye Field Supply]

Be very careful buying what appear to be cut rate HM Digital meters on Ebay - the site is LOADED with counterfeits. We're a Master Distributor for HM Digital and I just wanted you to be aware of the situation.

Russ

 

[H@rry]

I'm measuring the water the same way I have since '99. Without knowing the "numbers", I had membranes last for 2 years using the testing procedure that came with (and recommended by) Spectrapure. Now they don't last 2 months. I know I'm using more water now but not enough to be responsible for that much of a difference.

My question was to see if anyone in my area is having the same problem and maybe it is due to a change in our tap water.

I know how to test my membrane. I've been doing it for 13 years.

 

[Buckeye Field Supply]

OK.

Have you put pencil to paper and calculated how many gallons you've run through your carbon block and compared that the the block's capacity?

 

[Buckeye Field Supply]

Are you doing this with a Resilite?

 

[H@rry]

OK.

Have you put pencil to paper and calculated how many gallons you've run through your carbon block and compared that the the block's capacity?

No I haven't. I don't know how to calculate that. In fact, that was one of my questions about leaving the flush valve open for maybe 15 minutes and running all that water through the carbon block.

Are you doing this with a Resilite?

I guess that might be what it is. Whatever came on the Spectrapure units in '98 or '99.

My whole question is that something has changed in the last year of so because the membranes lasted much longer in the past.

 

[Buckeye Field Supply]

Take a 1 gallon milk jug and capture your waste water when you have the flush valve open - time how long it take to fill it up. Given that you'll be able to calculate gallons per minute

 

[Chameleon]

just curious, have you considered taking off the flush kit(or just stop using it) to see if it gets better? you mentioned that the problem coincided with the flush kit use. maybe go back to what was working well. I am not sure flush kits are all they are said to be. I had one on my old unit that I sold, but decided against one on my newer unit.

sorry I can't help on your real question about water quality I am just thinking of other possibilities.

BTW a 14 year old RO/DI system is impressive!

 

[H@rry]

Tyler - yeah, I'm not going to try to flush the new membrane and see how that works. I remember the first membrane lasted better than 2 years without being flushed. 2 or 3 years ago the unit took forever to make water until I replaced the membrane. I decided that the old membrane had become "clogged up" and that a flush valve would correct that. I now suspect that all the flush water is depleting the carbon block filter and then allowing chlorine to degrade the membrane.

We'll see.

 

[Dave3112]

Don't know what ever came of this but I thought about this thread when I read your post. FYI I didn't read all the way through the post just now either. it's past my bed time over here in Korea. LOL

https://www.reef2reef.com/forums/no.../58532-city-huntsville-switch-chloramine.html


You are only limited by what you allow yourself to dream.

 

[H@rry]

Thanx Dave, I read that a while back and emailed somebody at Huntsville utilities asking about chlorimine. He replied that Huntsville Utilities uses chlorine.