RO/DI problems

[holy carp]

OK, so I'm not certain if this belongs under the water chemistry or equipment forum, but since it's RO/DI, I'm trying it here.

 

I have a little RO buddy with the DI resin cartridge that I got last April and started using in June for about 5-7 gallons per week. For sure, that thing was never a fast producer, and even when new took an hour per gallon. Yesterday I made about 5 gallons and thought it seemed to take a bit longer than usual (recently 5 gallons was taking 6-7 hours, and yesterday seemed to take closer to 9-10 hours).

 

Oh well, I thought I'd let it run overnight for another bucket. So from 11pm to 9am, I got about 1 more gallon.

 

What's going on? First I thought sediment or carbon were clogged, so I took out the RO cartridge and ran water through with the DI at the end disconnected. Seemed to come through OK.

 

Then I replaced the same RO cartridge, left the DI off, and ran it.

 

I got a crazy waste-to-RO ratio:

 

OK, so that's not very precise, but I'm guessing about 20:1.

 

Now my tap water comes out at about 46 TDS. The waste water is 49, and the RO water is 20. If I reconnect the DI, it comes out at 0TDS, but probably reduces the ratio even further.

 

Is this thing shot already? I'm not sure if I should try replacing certain cartridges or just chuck it. Seems like the cartridges cost almost as much as the unit did to begin with (the whole thing was $90 w/ DI)

 

Thanks for any insights and inputs.

 

[CronicReefer]

Spectrapure is the way to go. Some of the best quality filters on the market and a great price.

 

http://spectrapure.com/RO-RODI/RODI-SYSTEMS/Aquarium-RO-DI-Starter%20Kit-Includes-RODI-System-Replacement-Filter%20Kit-TDS%20Meters-Chlorine-Test-Kit

[AZDesertRat]

You are missing two important pieces of information used to troubleshoot your system, water pressure at the membrane and water temperature. Without those two it's impossible to tell you where you should be looking at for replacement of upgrades.

 

Unfortunately your story is pretty common and units such as that give RO/DI a bad name.

 

I hate seeing people waste good money on the so called portable systems when for $125 they could have a real reef quality system with 1 micron standard size 10" filters, a treated and batch tested high rejection rate RO membrane, a full size 20 oz refillable vertical DI filled with fresh reef specific resin, an inline pressure gauge and a capillary tube flow restrictor that the end user can adjust to fit their water conditions. Doesn't make any sense to me?

[holy carp]

Thanks. I sure wish I knew you could get something good for $125, because saving $35 would not have been a priority. Oh well, live and learn.

 

I don't have any pressure gauge, but I believe it's usually pretty strong in apartment buildings. (At the least, I can say that flushing the toilet has no effect on shower temperature. ) I can check the water temperature at the tap tonight. Unfortunately, in an 85 year-old building like this, the temperature on the cold line can be pretty inconsistent both seasonally and throughout the day - those are long pipes in the walls running in close proximity to 150° hot water pipes and how long the water warms in the pipes is a function of how many people in the building have recently been using water.

 

Would you recommend the same system that Cronic linked to? Would those be more forgiving of varying input water temperatures? Given the prices you two have mentioned, I'm inclined not to invest in any new filters and put that money towards a new system instead. However, if there's anything I can do to milk more water out of this RO Buddy in the interim, I'd love to do so. Because if all I've gotten is about 200-300 gallons, that cheap little thing ended up making pretty expensive water.

 

[no694terry]

hows your feed line hooked up? Mines one of those clamp on needle valves and it make a big difference on my pressure, if its just open far enough for me to hear its running then i only get about 30psi at the membrane, once its fully open i see about 75psi at the membrane. Your issue is probably water pressure. Showers only let out about 2.5gpm so even at 30psi it will still flow fine and you may be used to it. You really need to order a inline valve to go before the membrane to monitor pressure, this is how you also know when you need to sediment/carbon filters

 

http://spectrapure.com/Pressure-Gauge-Kit-w-1-4in-push-fittings?filter_name=pressure%20gauge

[AZDesertRat]

Your rejection rate or removal efficiency with that membrane is only 56%, it should be 96-98%. The DI resin is doing all the work.

 

One thing you can try is to install a needle or ball valve on the waste line and adjust the waste ratio down to around 3:1 to 4:1, this will increase the pressure available to the membrane and should improve the rejection rate.

[holy carp]

Mine is connected to the bathroom sink with a hose adapter. Cold water is on full, so there shouldn't be any flow restrictors. Is too much pressure an issue, or just too little pressure?

 

Sounds like most people in the spectrapure camp, but I have to admit that their number of different systems and configurations has always been somewhat overwhelming.

[AZDesertRat]

The flow restrictor is installed in the RO waste line and is what makes the system produce water. Earlier you stated you had about 20 waste to 1 good so you need to either install a capillary tube flow restrictor in your waste line and trim it for your exact water conditions or install a ball or needle valve on the end of the waste line and throttle the waste to 4:1 waste to good.

High pressure is a great thing, membranes get more efficient the higher the pressure is. And remember, cold water only, never try to blend hot and cold or warm the water.

[holy carp]

Thanks. I don't like to trust hot tap water for anything but showering and washing.

 

I'll try to find a little valve to make adjustments. I was under the impression that the little cylinder on the RO waste line was some type of pressure regulator that maintained a proper ratio.

 

[AZDesertRat]

That is a fixed orfice flow restrictor but it doesn't look like it is hooked up if that is a red plug I see in the end.

I don't like or trust fixed restrictors since not everyones conditions are the same.

[holy carp]

Got it. I just quickly photograbbed that image from the net for reference. You are right - the image is from a photo of a new unit before the waste water line is connected where the red plug is. I'll have to look into a different restrictor that can be easily connected.

[AZDesertRat]

Look up "capillary tube" at places like Spectrapure or Buckeye Hydro. Get an untrimmed tube which looks like a piece of uncooked spaghetti with a small flange on one end. You toss whatever you have, disconnect the waste line from the membrane housing and stick the capillary tube inside the 1/4" waste line and reconnect. Run the unit and measure the waste with a measuring cup then remove the tube, trim it to the length recommended in the directions for your measured waste then reinsert and make water. Cost $5-$6.

[holy carp]

I researched those capillary tubes. I couldn't find any that were designed to be trimmed - they all came at a certain flow rating. Presumably anything with less flow than you need could be trimmed to more flow by shortening it.

 

However, last night I wanted to test the unit a little more. After turning on the water supply, I got 0 water out of the product line, and what flowed through the waste line wasn't extremely fast either, so I tried the following:

 

Tap through system - all water slowly passes through waste line.

Tap directly through sediment filter - passes through but not very fast.

Tap through sediment and carbon - passes but very slow.

Tap directly through RO canister and DI - runs through pretty quickly and appears to be at a reasonable waste to product ratio

 

I didn't have time to really measure anything with a stopwatch and measuring cup, which I could tonight, but I'm under the impression now that some of the prefilters (sediment, carbon, or both) are not allowing sufficient flow or pressure for the RO membrane to work. Given that, I'm thinking that a capillary tube would only build up sufficient pressure if it forced the flow rate down to something super low below the rated output of the unit.

 

Not sure if this info helps anything.

[AZDesertRat]

You can find untrimmed flow restrictors here:

http://spectrapure.com/FILTERS-MEMBRANES-RESIN/RO-MEMBRANES-FLOW-RESTRICTORS

All those labelled "standard" are untrimmed full length and come with trimming instructions or you can look on pages 6-10 here or in any of Spectrapures owners manuals for instructions on how to set it up:

http://spectrapure.com/manuals/MARINE-PRO-DI.pdf

 

With only the sediment or sediment and carbon filters you should have no restriction at all, the wate rshould jet through it with 0 psi drop. An inline pressure gauge is a must have item on any RO or RO/DI system, it is the number one tool for troubleshooting the prefilters with a low range chlorine test kit also useful for the carbon condition.

 

Right off I am guessing your sediment and carbon filters are plugged and need replacing. Sucks with the portable systems since you cannot see the filter like on good reef RO/DI systems where they are larger 10" filters and placed in clear housings with a pressure gauge to test them.

 

If the water runs quickly through the RO and DI then you have a ruptured or torn membrane, it should be a steady drip is all on the treated line and about 4 times that drip rate or a slow stream from the waste line. I assume you have a 50 or 75 GPD system which would equate to about 4 to 6 ounces a minute treated wate rat 77 degrees F and 50 psi. Any more than that andsomething is definitely wrong.

 

Flow restrictors are what makes the whole system work, without the proper amount of restriction on the waste line nothing goes through the RO membrane. You are forcing tap water through a plastic fabric that has pores in the 0.0001 micron range, that is atomic or ionic size, it doesn't pass through without the built up back pressure.

 

Honestly, if it were me I would start over with a new reef quality RO/DI and chalk this one up as a laearning experience. If you need a membrane, flow restrictor, sediment, carbon and DI filter you will spend as much or more than this and still have a low end system:

http://spectrapure.com/Refurbished-90-GPD-RODI-System

 

or even better on sale with a TDS meter, low range chlorine test kit and full set of replacement filters and reef specific 20 oz DI cartridge for only $35 more:

http://spectrapure.com/Aquarium-RO-DI-Starter%20Kit-Includes-RODI-System-Replacement-Filter%20Kit-TDS%20Meters-Chlorine-Test-Kit

 

Its not worth messing with the buddie.

 

I will also share with you that NY has some of the hardest to treat water in the US. Your TDS is low but your TSS or suspended solids are out of sight. So high the EPA is/was fining NY tens of thousands of $$ daily until they get treatment plants built and on line to treat the solids in the water. Spectrapure developed a 0.2 micron pleated sediment filter for just that purpose and had a bunch of users in the NY area beta test it under real conditions for a couple years before marketing it. It has 10x the surface area of a normal filter and believe it or not even though it filters down to 0.2 microns absolute, it has less headloss or pressure drop than a normal 0.5 or 1 micron sediment filter. And it can be carefully rinsed and reused several times. I use that filter myself in Phoenix and get two years out of it easily with no pressure drop.

http://spectrapure.com/FILTERS-MEMBRANES-RESIN/SEDIMENT-FILTER-CARTRIDGES/0.2-Micron-Absolute-ZetaZorb-Sediment-Filter-Cartridge-10-inch

 

Suspended solids plug up normal sediment and carbon filter very quickly leading to a ruined membrane since the carbons billions of tiny microscopic pores where the chlorine is adsorbed get fouled and the chlorine sneaks by to melt the TFC membrane which cannot stand any chlorine for long at all. Everything tells me yours is shot.

[holy carp]

AZDesertRat, thanks for such a comprehensive response.

 

Clearly the sediment filter is blocked - I guess I'm pretty surprised that it would happen so suddenly, but you've got me sold on getting a more robust system.

 

So from reviewing everything you've said, I expect the following:

 

The Spectrapure starter kit with replacement filters is a good place to start

The sediment filter won't last long because I'm in NYC, so I'm guessing I should start with the .2 micron filter straight off the bat and ditch the 1 micron pre-filter

 

Or am I better off selecting this chloramine one for a nominal price difference? If so, I'd still opt for the .2 micron filter to put in the first spot.

 

and in the end, I'll expect to get more than 300 gallons out of the system.

 

Once I order that and wait for it to arrive, do you think I can skip the sediment filter on the buddie and at least get a few gallons of decent water through it using carbon/ro/di? Or can I not trust it even if I get good TDS readings? (it may end up just being DI water, but that 'color changing' DI filter hasn't changed color yet at all). I'm overdue for a water change and would rather milk a few extra gallons than try to carry heavy water jugs on the bus/subway... (NYC living...)

 

Thanks again for all the good info.

[AZDesertRat]

If you have a TDS meter you can try and squeeze a little more out if what you have.

Chloramine filters are not needed. The only reason I would buy a chloramine system would be to get the extra canister which I would replumb into a dual DI. Inline TDS meters are a waste of money since they cannot be calibrated and are not ATC so lack the accuracy of a $25 handheld.

Yes, in your location I would highly recommend the 0.2 micron prefilters so it protects the carbon block. Between the pressure gauge and the chlorine test kit you should be able to get good filter life by monitoring operating conditions.

[holy carp]

Oh, why do I have so little will power.

 

I ended up ordering this:

http://www.marinedepot.com/ps_ViewItem.aspx?idproduct=SP12291&idCartRow=65903479&child=SP12291

 

along with the .2 micron filter to swap in the first canister.

 

I don't even know if that thing will fit under my sink, but what's wrong with a little overkill...

 

The good new is, this should last me for a bit.

[CronicReefer]

I have the same system...it's big. I've had it for a year now and it still performs as good as the day I bought it. Only had to replace the maxcap cartridge but I'd say I made at least 700 gallons before it was needed.

[martinicu]

this all new to me because I presently buy my ro/di at lfs. soon I will relocate from my home to a rental apartment upon retiring. I know you a have a background in the water treatment in AZ. can you recommend a system that I can use now in my home and take with me that will have an easy sink hook up. Right now I need approximately 5- 10 gallons per week its only a 12 gallon tank.

I just cant wrap my head around all the options. I know you will simplify it for me please. I'm will to spend the money for the needs that I have.

Thank you AZ

Edit: that should say willing

[CARBON]

I have the same setup (RO Buddie 50GPD with the DI cartridge). I have only made about 100 gallons so far with it, but my DI is half used up and my flow rates are: 1.25 gallons/hour clean and 5 gallons/hour waste.

 

TDS from faucet is: 227 PPM

TDS of clean water is: 0 PPM

TDS of waste is: 280 PPM

[AZDesertRat]

I don't think you can beat this deal anywhere.
http://spectrapure.com/Aquarium-RO-DI-Starter%20Kit-Includes-RODI-System-Replacement-Filter%20Kit-TDS%20Meters-Chlorine-Test-Kit

All you would need to add is a faucet adapter kit which can be purchased from any RO vendor or from a local hardware store.
Most of the bells and whistles you see on RO/DI systems are just that and don't add much if any value. By that I mean flush kits, chloramine carbons, multiple carbons etc.

[martinicu]

Thanks I appreciate it just got home

[holy carp]

So my new spectrapure maxcap came this week and I was going through setting it up this afternoon and flushing it out according to AZDesertRat's recommendations from a different thread. I think I might not have enough water pressure at the tap...

 

It's currently running with the DI disconnected and I'm getting a waste/product ratio of roughly 8:1 (2 cups waste and 1/4 cup product water), and the pressure gauge on the RO membrane is reading 25psi. I don't have a separate pressure gauge to connect to the tap directly.

 

Does this mean I need a booster pump or a different capillary tube? (It currently has the red one, which was pre-installed, but there's also a green one, which I believe may restrict waste water a little more)

 

Other notes:

cold tap water is running at 60°F

the DM-1 reads 55ppm in to membrane and 2ppm out from membrane

the TDS-3 reads 4ppm on the out

[AZDesertRat]

First thing I would do is kink the waste line to stop waste flow and see if or what the pressure gauges rises to. If it doesn't go up much then you need toc check your tap water connection to ensure you have a full opening and full pressure, check to see if you may have a pressure regulator on your incoming water line and buy a hose bib pressure gauge at the hardware store for about $8 to double check the pressure. It takes an absolute minimum of 40 psi to operate a single membrane system and 60 psi to operate a dual membrane system.

 

If it ends up you do have sufficient pressure then I would follow the directions starting on page 7 of your owners manual and see if either of the flow restrictors you have will work. If not you may need a new untrimmed one.

 

If you don't have sufficient pressure then an Aquatec 8800 booster pump may be needed.

[holy carp]

Thanks. I held my thumb on the waste line to completely stop flow for about a minute. The pressure gauge still read right at 27 psi. I also have it hooked up to a float valve in a bucket, so I lifted that until the water all shut off on both the product and waste side, and it still read 27...

 

Right now I have it connected to a hose adapter on the bathroom sink - faucet is on full, and so is the valve under the sink. I plan to move it over to the kitchen when I get a feed line adapter, but I assume the pressure there will be the same.

 

(if it's not flowing through at all like when the float is closed, that gauge should essentially read the pressure in the pipes in the wall, right?)

 

I'm in an apartment building (10th floor), not a house, FWIW.