Cryptic problem: RO membranes clog up. Please help

[rajdude]

old build thread here

rajdude's "house of horrors" tank!

www.plantedtank.net

 

[Spare time]

it is a 75 gallon + 30 gallon sump.

But it is not saltwater. It is a freshwater planted Discus tank, which for some weird reasons, I got convinced that re-mineralized RO water is best. Has CO2 injection and high power lights, like used in saltwater tanks.

Tank needs lot of water change for keeping Nitrates low :-(

I do have a refugium growing algae........like an algae scrubber. Does not make a huge difference for Nitrates though.

Ah. Some carbon membranes are only rated for a few thousand, so maybe the chloramines are using that up rapidly? I am not sure how that would change production speed as I don't think that can literally "clog" the carbon. I am curious what some others say

 

[rajdude]

Ah. Some carbon membranes are only rated for a few thousand, so maybe the chloramines are using that up rapidly? I am not sure how that would change production speed as I don't think that can literally "clog" the carbon. I am curious what some others say

So yeah, I have been wondering about that too. But the report says that the city uses chloramines only during a certain time....winter, I think.

But this problem happens both in winter and summer. Or maybe I am wrong, gotta look at my data a little bit more carefully...

 

[Spare time]

So yeah, I have been wondering about that too. But the report says that the city uses chloramines only during a certain time....winter, I think.

But this problem happens both in winter and summer. Or maybe I am wrong, gotta look at my data a little bit more carefully...

I like these threads. They are great learning experiences for me and everyone watching

 

[sneekapeek]

hmmm........because I am not aware of this thing Really? I can do an acid flush? Gotta look it up Unless you have a link handy

So people add anti-scalent to their water? How, is it injected or leached into the lines using, for example, in a housing + a block.......like what I use to re-mineralize the drinking water here?

Actually I do have electronic floats and solenoids in both brutes. (Should post a photo). They all worked well until the electronics behind them fried. I have not gotten around replacing that stuff.

What is wrong with using float valves? dribble meaning? Do they add back pressure? Is that bad?

Sorry, kinda a newbie to all this........hence so many questions.

What you’re seeing is a clogged membrane causing production to lower. I get this all the time fouling membranes prematurely. What I have found to remedy this is to acid flush once a month I would try running muriatic acid in your sediment filter chamber, screw it in, make sure it’s the last chamber right before the membrane. Disconnect DI from system. Disconnect permeate line and bypass to sink/tub/toilet drain. Then pulse the water line open close to fill membrane chamber. Let it sit in membrane chamber for 3-4 minutes. Run system to flush out crud for 5-10 minutes. Put sediment filter back in. Open drain to decrease pressure in membrane chamber and flush for another 5 minutes.
If you find yourself trying everything and not getting results, I’d try this as a last case scenario. It’s a lot of work when needed. At 174ppm incoming it seems like not very much, I’m used to seeing 770’s in San Diego! But I’d check your source.

RO machines are meant to be run at a certain gpm, pressure, water temp etc. I’ve seen membranes foul prematurely because when you use a dribble valve it reduces the permeate flow putting back pressure on system, btw your drain doesn’t slow down accordingly. You’ll make 1gpm and dump 2gpm. When dribble occurs you make 1/4gpm and dump 2gpm.

 

[Mike konesky]

"Fairfax Water uses chlorine for disinfection purposes, which can be harmful to fish if not dechlorinated prior to placing fish in it. Fairfax Water utilizes two types of chlorine, free chlorine and chloramines (chlorine and ammonia mixture). Chloramines are normally used July - March, and free chlorine is generally used April - June."

My guess is that your carbon blocks are exhausting and letting chlorine hit the membranes. .02ppm probably won't fry membranes like you mention, but .2 sure will. If your water was hard enough to scale up your membranes you would likely notice deposits on faucets, which you haven't. I'd recommend a smaller sediment to protect your carbons, and add another carbon.

 

[sneekapeek]

"Fairfax Water uses chlorine for disinfection purposes, which can be harmful to fish if not dechlorinated prior to placing fish in it. Fairfax Water utilizes two types of chlorine, free chlorine and chloramines (chlorine and ammonia mixture). Chloramines are normally used July - March, and free chlorine is generally used April - June."

My guess is that your carbon blocks are exhausting and letting chlorine hit the membranes. .02ppm probably won't fry membranes like you mention, but .2 sure will. If your water was hard enough to scale up your membranes you would likely notice deposits on faucets, which you haven't. I'd recommend a smaller sediment to protect your carbons, and add another carbon.

But the membrane would still make the same amount of water if chemically fouled. It would just increase the tds not slow down flow. Generally what I’ve seen is chemicals will change tds, minerals decrease flow!

 

[a.t.t.r]

A Freshwater tank with plants? If that is the case I would slow your waterflow on the output even more and just not care about some slight TDS creep ( your stuff already is failing fast just let it run until it dies and minimize waste water).

Also look into a simple denitrification setup and maybe grow something like duckweed in your fuge.

 

[LeftyReefer]

no, not excessively hard.

Tap water parameters at our house

GH = 143 ppm or 8 GH
(Moderately hard water)
TDS = 171


No we do not get deposits at all.

Yes, I flushed them before attaching output to membranes

Actually, If the numbers you posted are correct, then you do in fact have "HARD" water, not "Moderately Hard". See chart below.

Another thought I had was HOT water.... can damage membranes prematurely. Is it possible that your system is ever seeing HOT water?

Also, what is the intended waste to product ratio on your RODI unit? for instance, my RODI unit says it produces product to waste water at a ratio of 1:2.5 out of the box. It says for every 1 gallon of product water, it will produce 2.5 gallons of waste water, heading down my drain. If you are making 30 gallons of RODI every 2 days, that would be about 15 gallons per day. On my system, that would be about 38 gallons of waste water down my drain, each day. I don't think my water company would even notice that amount, let alone complain about it. how much waste water are you producing vs product water?

 

[rajdude]

What you’re seeing is a clogged membrane causing production to lower. I get this all the time fouling membranes prematurely. What I have found to remedy this is to acid flush once a month I would try running muriatic acid in your sediment filter chamber, screw it in, make sure it’s the last chamber right before the membrane. Disconnect DI from system. Disconnect permeate line and bypass to sink/tub/toilet drain. Then pulse the water line open close to fill membrane chamber. Let it sit in membrane chamber for 3-4 minutes. Run system to flush out crud for 5-10 minutes. Put sediment filter back in. Open drain to decrease pressure in membrane chamber and flush for another 5 minutes.
If you find yourself trying everything and not getting results, I’d try this as a last case scenario. It’s a lot of work when needed. At 174ppm incoming it seems like not very much, I’m used to seeing 770’s in San Diego! But I’d check your source.

RO machines are meant to be run at a certain gpm, pressure, water temp etc. I’ve seen membranes foul prematurely because when you use a dribble valve it reduces the permeate flow putting back pressure on system, btw your drain doesn’t slow down accordingly. You’ll make 1gpm and dump 2gpm. When dribble occurs you make 1/4gpm and dump 2gpm.

Hmmm. Thanks for posting the procedure. I must say it sounds scary to me.

I have used Muriatic acid in the past. For cleaning calcium deposits from my tank, when I bought it used, in a really dirty condition from a reefer dude. Anyway, that acid is strong man! Will the stuff inside the membrane survive?
Also you are saying I should put acid in the sediment filter, correct? Guessing I should take out the sediment block first, or let that block sit in the acid also?

I guess all acid needs to be flushed out. That can probably be achieved by runing water through it....but I wonder how long will it take for the membrane to be totally flushed out. I worry about fish dying if there is some stuff left in the membrane and ending up in the tank.

Just so I am clear, what are you calling "dribble valve"?
My system has two type of valves: Float valve or Auto Shut off valve. Which one are you referring to as "dribble valve"?

And what does it mean when you say ...."when dribble occurs..."

 

[LeftyReefer]

30 to 40 gallons EVERY 2 DAYS?????? So you are going through a 150 gallons from the faucet every 2 days? That is an insane amount. That is over a 1000 gallons in half a month.

That is nowhere near INSANE. Your toilets are probably still using way more water.

The average (non reefing) American household uses over 300 gallons of water per day. That's over 9000 gallons per month. Toilets account for 24% of our total water usage, so that's about 72 gallons per day in the average American household.

hmmm...first...thanks for looking at my water report

I wonder where that info is....I just downloaded the pdf file from here, could not find it, but since it is 32 pages long, maybe I missed it.

Anyway, it is what it is....I wonder if there is something I can do about it. These membranes are costing too much..............actually the waste water generated by this RO system is costing way too much! I get warnings from the water company every water bill.......urging me to check why I am using so much water. Seriously! :-(

Something seems way off here....

My system produces water at 1:2.5 ratio. If I were to make 20 gallons of RODI per day, my total water usage would increase by about 70 gallons (20 product, 50 waste) per day, which is still less than or equal to what your toilets are using each day.

if you flushed your toilet twice instead of once, do you think the water company would come knocking at that INSANE amount of additional water usage? I doubt it.

Something else seems to be leading towards increased usage if the water company is actually complaining. I find it hard to believe this RODI unit is using that much water... unless it is not setup efficiently, and wasting way more water than necessary.

OP is making a lot of RODI, but not enough that it should upset the water company.... I'm sure the house of 8 down the street is still using more water.

How much waste is being produced for every gallon of product water?

Are you sure you don't have a leaky toilet or plumbing somewhere leading to all this usage?

 

[rajdude]

"Fairfax Water uses chlorine for disinfection purposes, which can be harmful to fish if not dechlorinated prior to placing fish in it. Fairfax Water utilizes two types of chlorine, free chlorine and chloramines (chlorine and ammonia mixture). Chloramines are normally used July - March, and free chlorine is generally used April - June."

My guess is that your carbon blocks are exhausting and letting chlorine hit the membranes. .02ppm probably won't fry membranes like you mention, but .2 sure will. If your water was hard enough to scale up your membranes you would likely notice deposits on faucets, which you haven't. I'd recommend a smaller sediment to protect your carbons, and add another carbon.

So yeah, this was also discussed at length with the vendors. I am refering to "chlorine killing the membrane".
The general consensus was that if chlorine damages the membrane, I should see higher production of water but with high TDS. This is due to the presumption that chlorine destroys the membrane leading to more dirty water pass through.

Although it could be chlorine, but this problem seems more like something is clogging up the pores in the membrane, leading to loss in water production.

More info here:

Avoiding Testing Errors: Protecting RO Membranes from Chlorine Damage

Chlorine (Cl2) has long been an essential component in municipal, industrial and wastewater treatment due to its ability to eliminate most pathogenic microorganisms.

www.waterworld.com

To prevent oxidation on thin-film RO membranes, the feed water must be dechlorinated. Most membranes will have some chlorine tolerance before there is an observable decrease in salt rejection. Chlorine on the membrane can be discovered by an initial loss of membrane flux followed by an increase in membrane flux and salt passage.

For Dow FilmtecTM RO membranes, degradation can occur after roughly 200-1,000 hours of exposure to 1 mg/L of free chlorine. Unfortunately, chlorine damage is irreversible with any RO membrane, so proper steps must be taken to prevent it.

One drawback to the dechlorination process is that it can lead to biofouling on the RO membrane. For years, the standard operating procedure has been continuous chlorination and dechlorination of the feed water. Still, occurrences of biofouling after dechlorination are common. When chlorine reacts with organic matter in the water, it breaks it down into more biodegradable fragments. Unless the system is sanitized often, microorganisms can grow freely after dechlorination, since there is an enhanced nutrient offering but no chlorine on the membranes to act as a preventative.

Other dechlorination methods are growing in practice, such as applying chlorine off-line to the pretreatment section. All require careful monitoring and operating to prevent microorganisms from fouling the membrane.

 

[rajdude]

A Freshwater tank with plants? If that is the case I would slow your waterflow on the output even more and just not care about some slight TDS creep ( your stuff already is failing fast just let it run until it dies and minimize waste water).

Also look into a simple denitrification setup and maybe grow something like duckweed in your fuge.

you mean use a flow restrictor which lets less water pass?
Right now I have a 550ml

Yes, I do have ton of algae growing in the 'fuge. I harvest it weekly. I guess my high nitrates are coming from too large fish pooping too much and also maybe too many in a smallish 75 gallon DT. Right now I have 7 Discus fish in there, almost all are bigger than the palm of my hand.

 

[a.t.t.r]

you mean use a flow restrictor which lets less water pass?
Right now I have a 550ml

Yes, I do have ton of algae growing in the 'fuge. I harvest it weekly. I guess my high nitrates are coming from too large fish pooping too much and also maybe too many in a smallish 75 gallon DT. Right now I have 7 Discus fish in there, almost all are bigger than the palm of my hand.

Yes. And if you connect that second membrane you so the waste from the first feeds the second and then only have one restrictor on the second unit you can keep some rather good production rates.

like I said sounds like you are out of luck no matter what so I would shoot for less waste water and maximize membrane life. Just track your incoming/output tds and change it when it hits about 85 percent or so and if you are using DI resin I would just stop using it. I know some people will freak out at my less waste water recommendation but I used to make systems that would do hundred of gallons per day for LfS and maintained rejection rates for over a year with near nonstop use. Just do a 3 minute flush (bypass restrictor ) once per day.

 

[Lbrdsoxfan]

30 to 40 gallons EVERY 2 DAYS?????? So you are going through a 150 gallons from the faucet every 2 days? That is an insane amount. That is over a 1000 gallons in half a month.

If thats the case, no wonder the op is wearing out stuff so fast.

 

[rajdude]

Actually, If the numbers you posted are correct, then you do in fact have "HARD" water, not "Moderately Hard". See chart below.

Another thought I had was HOT water.... can damage membranes prematurely. Is it possible that your system is ever seeing HOT water?

Also, what is the intended waste to product ratio on your RODI unit? for instance, my RODI unit says it produces product to waste water at a ratio of 1:2.5 out of the box. It says for every 1 gallon of product water, it will produce 2.5 gallons of waste water, heading down my drain. If you are making 30 gallons of RODI every 2 days, that would be about 15 gallons per day. On my system, that would be about 38 gallons of waste water down my drain, each day. I don't think my water company would even notice that amount, let alone complain about it. how much waste water are you producing vs product water?

yes, I stand corrected My GH at 143 would be considered hard not moderately hard.

When I had the BRS dual membrane setup, its intended ratio was 1:1.5. Actual starting was around 1:1

Drain: with a 550 ml/minute flow restrictor (actually measures 475 /ml) = 180 gallon a day
Product: at the rate of 420 ml / minute = 160 gallon a day

But all that product flow reduces pretty fast.

Lets do math:

Last month, I changed the setup to single membrane setup. so now the initial ratio was 475 : 200 ml (1:2.375)

Waste is always measuring around 475 ml / minute. So if I am running the system 12 hrs a day, I am wasting 90 gallons
At the current rate of 90 ml / minute, my system is making only 17 gallons in 12 hours.....hmmmmm.....wait a minute! :-(

 

[rajdude]

That is nowhere near INSANE. Your toilets are probably still using way more water.

The average (non reefing) American household uses over 300 gallons of water per day. That's over 9000 gallons per month. Toilets account for 24% of our total water usage, so that's about 72 gallons per day in the average American household.



Something seems way off here....

My system produces water at 1:2.5 ratio. If I were to make 20 gallons of RODI per day, my total water usage would increase by about 70 gallons (20 product, 50 waste) per day, which is still less than or equal to what your toilets are using each day.

if you flushed your toilet twice instead of once, do you think the water company would come knocking at that INSANE amount of additional water usage? I doubt it.

Something else seems to be leading towards increased usage if the water company is actually complaining. I find it hard to believe this RODI unit is using that much water... unless it is not setup efficiently, and wasting way more water than necessary.

OP is making a lot of RODI, but not enough that it should upset the water company.... I'm sure the house of 8 down the street is still using more water.

How much waste is being produced for every gallon of product water?

Are you sure you don't have a leaky toilet or plumbing somewhere leading to all this usage?

hmmmm....you got me thinking now. I think I should measure again and re-calculate all this stuff.

Anyway, please check out what my water company shows for house's water consumption:

We moved in in July 2019. RODI was setup at the end of 2020. Its effects are probably visible in the bill for 1/30/2021
But why did it go down for 4/2021? Hmmmm

This is what it is showing today:

I did some calculations last year, when I started to worry about the high water bills

 

[rajdude]

Yes. And if you connect that second membrane you so the waste from the first feeds the second and then only have one restrictor on the second unit you can keep some rather good production rates.

like I said sounds like you are out of luck no matter what so I would shoot for less waste water and maximize membrane life. Just track your incoming/output tds and change it when it hits about 85 percent or so and if you are using DI resin I would just stop using it. I know some people will freak out at my less waste water recommendation but I used to make systems that would do hundred of gallons per day for LfS and maintained rejection rates for over a year with near nonstop use. Just do a 3 minute flush (bypass restrictor ) once per day.

yeah, that is exactly what the BRS water saver kit setup is. Check it out here

Water Saver Upgrade Kit

Why does BRS recommend this? Water Saving Upgrade Kits are probably our most recommended RODI upgrade. If you have proper pressure (65+ PSI) we highly recommend installing the kit, because it will produce water twice as fast as a standard 75 GPD or 100 GPD membrane while cutting the amount of...

www.bulkreefsupply.com

It did work really well at first, but clogged up pretty fast. Stats here:

I am thinking of removing my DI stage. Discus really do not need 0 TDS. They will be perfectly find at 7 TDS or so.

But the million dollar question still remains in my mind.......how to maximize membrane life?
I am also worried about all this water which is going down the drain.

As of today:
I calculate at least 90 gallons per day is going down the drain :-( That calculates to around 1400 gallons per month, assuming I run my RO water filter every 2 days for 12 hours, because of crappy production rates.

See that is the thing I do not understand.......how were you able to maintain rates over a year with non stop use? Did you have soft water out of the tap?

 

[rajdude]

If thats the case, no wonder the op is wearing out stuff so fast.

Yeah you could be right about "wearing out stuff"...............but which part in the RO filter setup is wearing out?

Membrane? (worn out membranes reduce flow or increase TDS in output?
Carbon blocks? (does not look like by looking at pressure and chlorine)
Sediment block? (does not look like by looking at pressure)

 

[sneekapeek]

Hmmm. Thanks for posting the procedure. I must say it sounds scary to me.

I have used Muriatic acid in the past. For cleaning calcium deposits from my tank, when I bought it used, in a really dirty condition from a reefer dude. Anyway, that acid is strong man! Will the stuff inside the membrane survive?
Also you are saying I should put acid in the sediment filter, correct? Guessing I should take out the sediment block first, or let that block sit in the acid also?

I guess all acid needs to be flushed out. That can probably be achieved by runing water through it....but I wonder how long will it take for the membrane to be totally flushed out. I worry about fish dying if there is some stuff left in the membrane and ending up in the tank.

Just so I am clear, what are you calling "dribble valve"?
My system has two type of valves: Float valve or Auto Shut off valve. Which one are you referring to as "dribble valve"?

And what does it mean when you say ...."when dribble occurs..."

You can leave the sediment filter in if you’d like! and fill the chamber halfway or all the way filled with muriatic. Probably 3/4 because it’s a screw in and it’s easier not to spill. It’ll clean whatever deposits out and flush out build up around the membrane!
Any valve that slowly rises. You want the shut off to be instant. The machine is either on/off. Usually valves that look like a lever are not good to have! Not dribble over time! You just want to make it so the unit runs at whatever gpm flow it’s intended for and then shuts off when it reaches capacity in holding tank. You don’t want the valve to close halfway reducing your flow and still wasting lots of water. It messes with the membranes.