Oconomowoc water question

[rica5tully]

I live in Oconomowoc and am having trouble with my RODI unit. I bought all new pre-filters, new membrane, and new DI resine about 3 months ago.

Yesterday I checked and my TDS is over 115! Anyone have any thoughts on that? Has anyone heard of water around here being so bad that it ruins your filters immediately?

Now I'm starting to grow cyano, which happens every time my RO water starts going bad.

Thanks,
ET

 

[jeffgp]

what is it to start with ...

 

[rica5tully]

Well, my new TDS meter (don't have one now) is on the way, so I haven't measured it yet.

Not to be stupid, but I don't understand why it matters what the original TDS is. Shouldn't an RODI bring anything to zero (theoretically)?

Or is it an issue of really high TDS destroying the filters faster?

Sorry, I'm kind of new to this.

 

[cschwaj]

The more unpure the source water, the faster it will "consume" the filtering ability of the various media. But what you are describing seems to be more than just dirty source water.

It is unusual, but not unheard of, to have to replace the membrane pre-filters that frequently. Once you get your TDS in hand, I would look at the unfiltered level and possibly some intermittent levels. I wonder if you have a bad membrane.

 

[Chads29]

I use an inline TDS meter and change out the prefilters often. The DI resin goes quickly if you don't change out the prefilters often enough. If you have questions call the filterguys and they will work with you to help you get the most out of your set up.

 

[tom obrecht]

You may have co2 in your water. I am on a private well and had super high tds to start with and when the math was done had co2 in the water which in turn burns di resin very quickly. You can go under spectrapure's site and they have a chart on how to measure co2 in your water. They helped me get my well water to 0 tds.

 

[prugs]

Recheck the RO tubing connections per the diagram. When I got my RO unit the TDS coming out was about 150ppm. The tubing was connected wrong from the manufacturer. That fixed my problem right away.

There are also different types of membranes CTA (cellulose triacetate), and TFC (thin film composite). The CTA units "do not" do good in a well water enviroment with possible bacteria sources.

 

[rica5tully]

thanks a lot for the help everyone. I'll call the company and talk to them about some of these things.

Thanks,
ET

 

[rica5tully]

Well, I just used a different TDS meter an my produced RODI water came out as 2 TDS! So the other one must have been really off or something.

1. Do new TDS meters come pre-calibrated?

2. Is 2 TDS o.k.? How high is o.k.? Or should it always be zero?

My origin water (Oconomowoc) is about 294.

Thanks,

ET

 

[jeffgp]

thats not too bad

 

[sero]

What temperature water are you putting into your filter? Hot water will destroy your membrane. Cold water will reduce your RO/DI's effecitveness a bit. Target temperature is something like 60 or 70F (correct me if I'm wrong here please, it's been a while!)

 

[jeffgp]

i thaught it was a bit lower 55-60 but im not even sure

 

[TropTrea]

RO units

RO units

I';ll give a little primer on RO systems since I have been running them for many years.

1. There are various elements in the membrane. These membranes have slightly different characteristics and effeciencies. The effeciency can rage from the removal of only 92% of the impurities to as high as 98% of the inpurities. These membranes are all somewhat vunerable to both bacteria and negative charged ions at different levels.

2. Failure of a membrane shown as decreased flow is the most common. What happens is the impurities that were being filtered out of the water simply accumilated and are blocking the membrane. the best solutions to this are having a prefilter of preferably 1 micron to prevent larger particals from entering the membrane stage. Another thing is to frequently backflush the membrane to push out a good percentage of the impurities that have accumilated on the membrane before they start restricting the flow.

3. A less common failure is caused by increase of TDS in the filtered water. This is generaly caused by either of two things.
a. The chemical reaction of negative charged ions on the membrane slowly allowing larger particals to slip through. Usually this occurs with chlorinated water however other chemicals added to the water can cause simular issues like florides. The best help here either switching to a HSi membrane as well as making sure you have a carbon prefilter that is changed regularly.
b. Some bacteria will also start eating away at the membrains. While these are difficult to counter in a prefilter if it turns out to be a repeated problem the switching to a HSi membraine will lessen the ability of the Bacteria to destroy it compared to a CTA membrane that is extremly vunerable to bacteria. A 1 micron prefilter will also decrease the amount of bacteria reaching the membrane.

4. On initial start up always run the first 50 to 100 gallons of water into the drain from a new membrane. There are two reasons for this, the manufacturing impurities need to be flushed from the membrane as well as the membrane needs to adjust to the flow in order to give the most effecieny and will ocassionaly produce water with a higher TDS initially.

My personal recommendations
A. Get a HSi membrane they may cost a little more but are much more effecient and last much longer.
B. Use a Carbon Prefilter if there is the slightest possibility of Chlorine in the water.
C. Use a 1 micron prefilter and if possible a 10 micron prefilter before that. The prefilters are much cheaper to replace than membranes.
D. Back flush you membrane regularly. On a rough schedule IO would say when you about 10 days of water it is time to backflush. I have found that this will extend the life of the membrane by 2 to 3 times compared to not back flushing. If you have a high yield system a membrane can cost well over $100 alone and replacing it evey 18 months is much better than replacing it every 6 months and is well worth the 5 minutes it takes to backflush every 10 days.

Dennis

 

[rica5tully]

Thanks. How would I backflush my membrane? Should I just reverse the ends and run the water the wrong direction? Or do I take it out and rinse it with water and put it back in its case?

ET

 

[prugs]

I have been using RO systems for over 13 years. I have never back flushed a membrane, & I have well water.

 

[TropTrea]

And how often do you have to replace membranes?

When I had my store I needed about 100 gallons of RO water every day. My first membranes there only lasted under 6 months. I wrote Kent MArine complaining about the life and they strongly recommended a high pressure punp as well as a back flush kit.

I opted for the backflush kit when I installed the new membranes. I got 3 1/2 years ot of thos membranes running them 24/7 and then brought them home. Unfortunatly the fire destroyed them and I had to replace them. Fortunatly I do not see a need for 100+ gallons per day so I simply got a 35 gpd HSi unit.

I would never purchase anything except the HSi membranes any more.

Dennis

<a href=showthread.php?s=&postid=10448827#post10448827 target=_blank>Originally posted</a> by prugs
I have been using RO systems for over 13 years. I have never back flushed a membrane, & I have well water.

 

[prugs]

<a href=showthread.php?s=&postid=10452363#post10452363 target=_blank>Originally posted</a> by TropTrea
And how often do you have to replace membranes?

The first one lasted approx 11 years, before I replaced it with a larger unit. But I'm not processing 100gpd.

 

[TropTrea]

Yes how much your processing plus how much your filtering out have a direct effect upon how long your membranes will last.

As an example say your filtering out 300 ppm of impurities, at 100 gallons per day for 1 year you would have a total of 10.95 units, someone else with that same sized unit might be running it only one day a week and there filtering out 400 ppm so it would take them 5.25 years to filter out that same total amount of matrerial.

In that case the membrane would last at least 5 times longer for the second user even though had more things to filter out of his water.

An interesting thing I would love to see is the water filteration system for one of the fish importers in the LA area. I have been told they have around 3,000 tanks averaging 80 gallons each, and have a system that automaticly changes 20% of there water every week with RO water. This would mean almost 7,000 gallons of RO water per day. With the waste from a RO water system and the high cost of water in the LA area I wonder what there water bill looks like? And what there bill for the other chemicals that they need to add to the RO water is since no fish can survive in water with 0 hardness.

Dennis

<a href=showthread.php?s=&postid=10453614#post10453614 target=_blank>Originally posted</a> by prugs
The first one lasted approx 11 years, before I replaced it with a larger unit. But I'm not processing 100gpd.

 

[jmkarcz]

I am frequently reminded by Jandlms in our group that just because your TDS is above 0, it is not nessecarily a bad thing if it's the right kind of TDS...

For example, Kass has a high TDS reading, but it is mostly from calcium or something else her tank USES, while, my city water generates the ecentual build up of Phos...

Are you having a problem? I found that I am changing my stage one filters every 45 to 60 days. PERIOD. and the stace 2 carbon block every 60 to 80 days. (usually every other time) This is a schedual recommended by the filter guys. You may want to watch it for a a period of time, (TDS) and I would still calibrate it... and detail oriented when you test by waiting 15 to 20 minutes after its running and swish out your test container several times with test water.

Watch how long you can go before your TDS climbs.

I was at my wits end with the RO system 2 years ago... everyone seems to stop helping you after you invest in a filter cartridge... but the Filter Guys spent time with me and talked me in from the ledge...

Jason
FVRC
Green Bay