High PPM from my RO unit

[Ruud]

Another day, another issue, another question

About a year ago I bought a RO unit, the typical 3 stages with an osmosis membrane at a fish shop. Supposedly specific for fish keeping. I hooked it up to my hard water tap and produced water that had 320 PPM (my tap water runs at 415). I had poor pressure, around 40psi so figured that was the main cause. I got a pump to increase pressure but never got to hooking it up and did use the 300ppm water for some tanks. 

Last week I finally hooked up the pump and ran my water at 75-80psi.... same result - 320PPM but with a year old system and a 200GPD membrane. Today I changed all the filters - now running a new 50GPD osmosis membrane, PP, GAC and CTA filter  and running at 80psi... and I get RO water of 280ppm (still 415 from tap). So the Osmosis system takes out roughly 30% of the particles only..

Now I am not the smartest around this kind of stuff.... but this should produce under a 100ppm water easily, right? What am I doing wrong here - any suggestions? 

Thanks so much! 

[TOtrees]

Ya something ain't right. I would guess you have something connected wrong. Also, how are you measuring the tds/ppm? Your best bet for this is an inline sensor, like this:

This will let you measure tds at different points in the flow/system. 

Maybe share some pics of your setup? 

It's also possible that something in your water is really really instantly fouling or clogging the membrane. Unlikely, but possible. You're running sediment and carbon filters before the membrane, yes? 

In terms of target/expectation, even without a DI resin, you should be able to get under 10ppm with a new membrane. That number will climb with use, and how much/how fast will depend on the water you're running through it, and how much you're removing before the membrane (eg sediment/carbon filters). 

You can also try flushing your membrane, and see if that makes a difference. Here's how to install a valve to do it regularly https://www.youtube.com/watch?v=T5CFco_Ceog, but you can also do it by manually removing the flow restrictor. 

 

[Ruud]

I am measuring with a regular stick pen from Amazon, I have another older on that provides similar (slightly higher) values. Also when I measure water quality with a test strip I still have a PH of around 7, GH of around 4 etc so pretty sure it's reasonably accurate

Yes - I am running sediment and carbon filter before the membrane, and another carbon filter after the membrane. The system came pre-connected, just had to connect inlet (that goes into the sediment, through the pump) and the out line and waste line - so nothing I could have screwed up I think.  

Maybe I should toss out the system and buy another system, bit lost here tbh . Let me make a pic and upload it. 

[Ruud]

Here it is. White tube on the left filter is my RO out tube. Top tube on the right is the waste tube, lower tube on the right (into the sediment) is the tap water IN tube that runs from the pump. 

First stage sediment, then pressed carbon, then RO membrane, then granulated carbon

Edited November 3, 2023 by Ruud

[TOtrees]

Did you buy it used, or new? I'm sensing used. 

I'm very very far from being well qualified in this, but I've never seen carbon after the RO membrane. Is that perhaps supposed to be the DI resin? That does commonly come after the RO. If you've put granular carbon into the DI cartridge... 

 

[Mmiller2001]

Should be near 0 with a good system. I’ve also never seen carbon after either. Might be worth it to replace the system with something better.

I’ll get 1 to 2ppm water when my DI resin depletes or filters need to be serviced.

[Galabar]

My understanding is that an RO system will generate 5 gallons (or more) of "reject" water for each gallon of "good" water produced.  Is that what you are experiencing?

Most of your water should be going down the drain (or to your garden?) for an RO system...

Edited November 3, 2023 by Galabar

[anewbie]

On 11/3/2023 at 3:18 PM, Galabar said:

My understanding is that an RO system will generate 5 gallons (or more) of "reject" water for each gallon of "good" water produced.  Is that what you are experiencing?

Most of your water should be going down the drain (or to your garden?) for an RO system...

Even a horrible ro system will do better than 5 bad to 1 good; the best small system does 1:1; the common system does 2:1 or 1.5:1; a very good very large system might do 0.5:1 not sure where you see 5 bad to 1 good.

 

[Galabar]

https://americanhomewater.com/the-truth-about-reverse-osmosis-waste-water/

Quote

You’ve probably heard that the reverse osmosis waste water ratio is 4:1. In other words, these systems use four gallons of water to purify one. 

While this is accurate from a numerical standpoint, we hope this article has shown you that saying reverse osmosis systems are wasteful is a bit misleading.

https://premieresales.com/how-much-water-does-reverse-osmosis-waste/

Quote

Returning to the main question: do reverse osmosis systems waste water? The answer is yes and no. Depending on the type, quality, and age of a system, they can produce 3 – 25 gallons of waste water per one gallon of product water.

Regular system above: 15 gallons to 2 gallons

High Efficiency system above: 6 gallons to 2 gallons.  Note that this high efficiency system costs around $500.  This efficiency will only be obtained if you have sufficient pressure and you replace the membrane and prefilters religiously.

The above video estimates 96.5% water waste with partial files of the tank.

In the video above, the basic system might be 4 gallons to 1 gallon, but with a storage tank it can be 15 gallons to one gallon.

I'll stop now as there are just too many sources to confirm what I originally said. 🙂

Edited November 3, 2023 by Galabar

[anewbie]

On 11/3/2023 at 6:40 PM, Galabar said:

https://americanhomewater.com/the-truth-about-reverse-osmosis-waste-water/

https://premieresales.com/how-much-water-does-reverse-osmosis-waste/

 

Why don't you look at the specs of the typical home ro unit used for aquariums also how is this related to @Ruud issue ?

 

btw @Ruud ro unit are fairly straight forward; either the membrane is bad; the water is by passing the membrane or something isn't hookup right. I had a similar problem with a new ro unit and i couldn't figure out the problem so i just had the vendor replace it and that solved the issue - and at least when the membrane is new the ppm should be below 10 and generally close to 0.

 

One other issue the pressure need to be in the range the unit requires to work properly. 

Edited November 4, 2023 by anewbie

[Sarina]

On 11/3/2023 at 11:44 AM, Ruud said:

First stage sediment, then pressed carbon, then RO membrane, then granulated carbon

This is most likely your issue. This is how I have my RO system set up: 
Sediment -> granulated carbon -> pressed carbon -> RO membrane -> DI membrane

You should never have a stage after the RO membrane unless you are also using a DI filter, and running water that has not been properly put through a dual stage carbon before hitting the RO membrane can ruin it. You will likely need to replace your RO membrane after you rearrange things. 

[Galabar]

On 11/3/2023 at 4:46 PM, anewbie said:

Why don't you look at the specs of the typical home ro unit used for aquariums also how is this related to @Ruud issue ?

Those links were in response to your post:

On 11/3/2023 at 4:22 PM, anewbie said:

Even a horrible ro system will do better than 5 bad to 1 good; the best small system does 1:1; the common system does 2:1 or 1.5:1; a very good very large system might do 0.5:1 not sure where you see 5 bad to 1 good.

None of the research I did could confirm your claim and seems to show that I was correct (about large water loss).  I didn't want this thread to spread misinformation.

As to @Ruud's particular unit, I couldn't find it.  I'm wondering how old it is (or if it is sold outside the US).  I'm guessing this is just a standard unit with significant water loss.  I initially brought up the water loss to make sure that @Ruud was actually seeing significant water loss, as not having any (or much) might show a perforated membrane.

So, again, @Ruud what are you seeing coming out of your waste port as opposed to your "good" port?  From the links and videos above, you should see something like 5 gallons (could be much more or a little less) for every 1 gallon.  Note that the membrane has a flow restrictor, which is responsible for restricting the flow of reject water: https://www.bestrowaterpurifier.in/blog/ro-flow-restrictor/.  If there is something wrong with that, I'm wondering if you might not have enough rejected water?

On a side note: definitely don't use a tank if one came with it.  Just have the "good" water empty into a brute trash bin or other container.  You'll get much higher efficiency (I learned that from the videos above).

Another side note: I did find a system that could do 3:1 (and 800GPD!!!), but it cost $1000: https://www.amazon.com/dp/B0987FCQQW.  That might actually be cost effective for larger users.

Edited November 4, 2023 by Galabar

[Sarina]

On 11/3/2023 at 9:26 PM, Galabar said:

Another side note: I did find a system that could do 3:1 (and 800GPD!!!), but it cost $1000: https://www.amazon.com/dp/B0987FCQQW.  That might actually be cost effective for larger users.

This is the unit I want someday lol. The TDS meter in the faucet is so cool! 

[Ruud]

SO thanks for all the responses.... in all fairness I think my best bet is to just toss it away and get a run of the mill home unit which runs me back about 100 euro. 

So the unit is bought new - but not getting any of my hopes up in getting the shop or the seller help me out here. This is Spain, not USA. 

The unit came with the following setup : Sediment -> Carbon -> RO membrane -> Resin. I swapped the membrane and the whole filter setup for a replacement package (4.4 stars on amazon) that would give me the setup: Sediment -> granulated Carbon -> RO membrane -> pressed Carbon

For the comment on the missing resin, I swopped the last carbon back to the Resin of the original set.... and get 315PPM readings, so even worse. I have a lot of rejected water, less when I put the pump on at 80PSI. The set says it needs a pressure of 60-90PSI.

Again the system came fully hooked up so somewhere I think I just have a faulty system and perhaps my best bet with least headache is getting me something similar from our local home depot equivalent and see if that's a solution or not.

[jwcarlson]

Is there an RO membrane installed?  

If the replacement kit has the same issue I would be thinking there's a plumbing issue on the unit.  Can you find a connection diagram/picture in manual and compare? 

[Ruud]

Yup RO membranen is installed, brand new 50GPD unit. I have looked at the plumbing a 100 times... I can't find anything wrong, everything seems the way it needs to be. The manual and the diagram is super basic but looks to be exactly as is. I'm lost 

[Galabar]

That is so weird.  Yeah, maybe just get another unit.  From what I've been reading, you should see 25 ppm or under for an RO unit (I think that is without DI resin).

After a little research, this one looks pretty good (although you might be able to get something cheaper without the facet and storage tank): https://www.amazon.com/dp/B005LJ8EXU

https://www.123filter.com/ac/ispring-rcc7ak-uv-deluxe-under-sink-7-stage-reverse-osmosis-drinking-water-filtration-system-with-alkaline-remineralization-and-uv-sterilizer

 

Edited November 4, 2023 by Galabar

[anewbie]

On 11/4/2023 at 1:24 AM, Sarina said:

This is the unit I want someday lol. The TDS meter in the faucet is so cool! 

I wouldn't buy that unit for aquarium usage; it is design for drinking water which is a different application; the way it works the waste level are way high - almost outrageous - esp if you read some of the reviews carefully.

 

Drinking water 'ro' water is a different market with different design and constraints - they are intended for 'purification' of drinking water in area where tap water has a our taste or other issue. I suspect this is mostly true with well water; though marketing ropes in some other segments. 

However i wouldnt' trust one of these for critical aquarium usage; though for simply softening hard tap water they might be ok with extreme waste - i did not check into cost of service (replacing the ro filter for example - a lot of these unit use custom fitting parts so higher surcharge than your typical ro unit designed for aquarium usage).

On 11/4/2023 at 8:28 AM, Ruud said:

Yup RO membranen is installed, brand new 50GPD unit. I have looked at the plumbing a 100 times... I can't find anything wrong, everything seems the way it needs to be. The manual and the diagram is super basic but looks to be exactly as is. I'm lost 

Could it be a pressure issue; forcing too much water through the membrane too fast ?

[anewbie]

On 11/4/2023 at 7:58 AM, Ruud said:

SO thanks for all the responses.... in all fairness I think my best bet is to just toss it away and get a run of the mill home unit which runs me back about 100 euro. 

So the unit is bought new - but not getting any of my hopes up in getting the shop or the seller help me out here. This is Spain, not USA. 

The unit came with the following setup : Sediment -> Carbon -> RO membrane -> Resin. I swapped the membrane and the whole filter setup for a replacement package (4.4 stars on amazon) that would give me the setup: Sediment -> granulated Carbon -> RO membrane -> pressed Carbon

For the comment on the missing resin, I swopped the last carbon back to the Resin of the original set.... and get 315PPM readings, so even worse. I have a lot of rejected water, less when I put the pump on at 80PSI. The set says it needs a pressure of 60-90PSI.

Again the system came fully hooked up so somewhere I think I just have a faulty system and perhaps my best bet with least headache is getting me something similar from our local home depot equivalent and see if that's a solution or not.

That order is fine - you don't have to have the di phase; and it is kind of  a pia to use. With just the sediment filter and ro membrane you should see tds below 10. 

--

If you go with another unit (if in usa); bulk reef is the cheap route and spectrapure is the more expensive route; either way i would avoid getting a unit designed for drinking water for some of the reasons previously mentioned. 

-

One more comment on the pressure - if i understand you got a lower rated membrane for the unit - i think you said it was 100 gpd and you went with a 50 gpd unit membrane; but that membrane might also require lower pressure (not sure).

[Sarina]

On 11/4/2023 at 5:23 PM, anewbie said:

I wouldn't buy that unit for aquarium usage;

Cory himself recommends this unit, and the waste water issue can easily be resolved by increasing water pressure. Drinking water RO units are not any different filtration from the ones made for aquariums, the technology is the same and the resulting water is 0-20TDS. 

[anewbie]

 

On 11/4/2023 at 7:06 PM, Sarina said:

Cory himself recommends this unit, and the waste water issue can easily be resolved by increasing water pressure. Drinking water RO units are not any different filtration from the ones made for aquariums, the technology is the same and the resulting water is 0-20TDS. 

Not sure - this was the review that bothered me:

-- (from amazon)

I'm really disappointed with this product. We were all excited to have great tasting water, I bought the mini pressure tank to use for our refrigerator, the mineral adding filter, and a refrigerator line kit. I noticed after a single glass of water that the flush would kick on after 5 minutes. You could hear quite a bit of water being wasted. Today, I decided to measure how much water is wasted. For one 16 oz glass of water, the waste produced while filling the glass does appear to be about 1/3 or 5.3 ounces of water. Perfectly acceptable. But then after 5 minutes the auto flush kicks on and runs for 1 minute. This wastes approximately 48 ounces of water. For 1 glass of water!!! Next I decided to fill a one gallon container. Again during the fill it wastes very little water. 5 minutes later the auto flush kicks on and wastes 64 ounces/half gallon of water. This is a little more acceptable, but not near their claim of 3:1. This system might be great if you planned to fill a 5 gallon container every time, but who on earth would use it this way?!?! Luckily I'm still within my return period, so sadly this thing has to go back.

-- 

It seems to have a auto flush design that kicks in - the review make it sounds like every time you use it in a 5 minute period but i'd have to do more research ot determine actual frequency. So for example in my specific case with a drip system - so for a 1 hour period it would generate 2 gallon of ro water but auto flush would kick in 12 time and each time 48 oz per run or for 256 oz of water produced it would waste 576 oz - now in all honesty this is based on a review and i would need to do more research to figure out how the auto flush works and if it can be adjusted/configured but it raised a red flag resulting in my comment.

-

Also it has no di stage; this is not strictly required and in some cases useless but it can be helpful in cases where it is needed - not so much for removing a few stray particles left but removing ion for lower ph. Again this is usage specfiic.

 

Edited November 5, 2023 by anewbie

[Galabar]

Yes, that unit does seem a little fishy:

Quote

I owned the 400 series for a while. When the time came to replace, I decided to upgrade to the 800 series. Who wouldn’t want faster water output and less water waste? What I noticed right away was that a few minutes after you dispense water, the system starts flushing the filters for about 40 seconds. I called customer service to inquire about this, thinking it was a problem with my particular unit. I was told that this is something that 800 series does. It flushes all the filters for 40 seconds after each water dispensation. This wastes about a quarter of gallon of water. in other words, you may have filled an 8 ounce glass of water creating minimal water waste but later the system wastes another quarter of a gallon to flush the filters. The system is noisy which I can allow for while I’m dispensing the water, but the filter flushing feature with all the noise and creates is quite annoying when you’re no longer at the sink.

RO units reject water so that the membrane doesn't get clogged.  This unit seems to have found a "clever" way around that by rinsing the membrane after dispensing water.  I'm guessing this just wouldn't work if run continuously.  It is meant to give you a glass of water, claim a 3:1 waste ratio and then stealthily waste water after you cup has been dispensed...

[Mmiller2001]

Stop over thinking this, just buy a bulk reef supply system and problem solved. It wastes water, they all do, who cares. Run the waste down the drain to be recycled.

[Galabar]

On 11/4/2023 at 10:12 PM, Mmiller2001 said:

Stop over thinking this, just buy a bulk reef supply system and problem solved. It wastes water, they all do, who cares. Run the waste down the drain to be recycled.

I'll second that.  🙂

I notice that some folks add some of the waste water back into the RO water.  With the correct proportions, they get the GH and KH that they want (and save some water).

Edited November 5, 2023 by Galabar

[TOtrees]

@Ruud I keep going back to why you're getting the numbers you are. Now that you have removed the carbon after the membrane, whether you have DI resin or not should only make a difference of a few ppm. With or without DI resin, a new system should get you under 10ppm, easy. 

Are you sure that you are collecting/measuring/using the pure filtered water and not the rejected water? In the parts of the thread/responses above, various writers talk about the ratio of good to bad or rejected water. The high ppm numbers you are getting are consistent with what your waste water should be. Your membrane housing should have 1 input and 2 outputs. One of the outputs is waste (which should have a flow restrictor after the membrane), and the other is the water you collect. 

And above, you wrote that you have a new membrane, right?