RO/DI not making good water.

ReeferBen · Jan 31, 2015

I don't have a hand held TDS meter so do not know my starting TDS but it's never been out if the ordinary.

I have a vertex RO/DI, it has a built in booster to keep it at 50 psi. The problem is the buIlt in TDS meter shows the unit producing over 50ppm in the good water. I bought a new membrane since when I switched the carbon/prefilter/DI the DI lasted less then a week. It has been over a year and a half and I used the unit heavily.

I put the new all new filters in, new membrane and all and left the DI empty to see how the TDS read with the new membrane assuming it would be under 10. It was still 50. I saw no waste water and pulled the tubing out and found the restrictor was clogged I cleaned it and put it back in. Waste water and production water seem to be at the correct level now but the unit is still flashing 50ppm which means 50+.

Thinking I just need to run more water through the membrane but it has been running about 2 hours and is a 100gpd. What do you think?

mtfish · Jan 31, 2015

I would take the membrane out again and try to reseat it. Could be leaking past the seal and not completely pushing all the water through the membrane. It would be nice to know what your initial TDS is so you could have some idea where you should be. Not sure what else to do to help you out. Good luck.

Triggreef · Jan 31, 2015

Just having read my instructions that came with my replacement ro... It says to run the filter for about an hr without the di installed prior to using any of the water. I see you saying your done that for about 2hrs now.

Did you by any chance change the size of the ro membrane compared to the one you previously had? If you change what the output is, you also need to change to the appropriate flow restrictor.

Fin · Jan 31, 2015

I think I would double check the TDS of my product water with another meter before I spent too much time trying to figure out what is wrong with the unit. It might be a bad meter on your unit.

AZDesertRat · Feb 1, 2015

The Vertex systems I have personally seen have all failed prematurely due to insufficient waste causing the membrane to plug up with solidified TDS since it has to go somewhere and normally that is down the drain.

Since 90-98% of the work is done by the RO membrane it is critical that it stay flushed via the 3:1 to 4:1 waste ratio which is the industry sandard. Some such as this unit have unsuccessfully tried to reduce the waste to 2:1 or even 1:1 and the result is short membrane life and increased cost of ownership due to more frequent replacements.

In some cases it is possible to reduce the waste ratio from 4:1 down to 3:1 and in rare cases to 2:1 but ONLY if you have softened water and lower than normal tap TDS and you make water in large batches versus short spurts.

You need to get your hands on a good reliable handheld TDS meter such as a HM Digital TDS-3, TDS-4TM or AP-1 and a calcium carbonate water hardness test kit. Once you do so tell us what your hardness is, what your TDS is, your water temperature and your water pressure along with your exact measured waste ratio both with and without the booster pump in use. The inline TDS meters have issues such as not being able to calibrate them, they are not temperature compensated so can be significantly off and they are limited to the two or so points monitoring when for an RO/DI you need at least 3 points if not more. The handhelds mentioned are ATC temperature compensated, can be user checked or calibrated and can be used portable to test anywhere including the important tap water and between DI cartridges if you have dual DI.

There is one long term proven low waste system still on the market today, the Spectrapure MaxCap UHE, but it is very different than any other. The biggest difference is it uses stored DI water to flush the RO membrane on a timed basis via a computer microprocessor then to double flush and pickle or store the system soaking in DI water each time it shuts off so it is cleansing the membrane at all times when not in use. I have owned this system myself for over 7 years and it has been flawless.
My tap water TDS is around 600 and the water hardness is around 20 grains per gallon so I do use a Sears water softener *** it. The original RO membrane is still installed, my tap water pressure averages 68 psi, water temperature varies between 57 and 65 degrees, I operate the RO booster pump at between 95-100 psi and the measured waste ratio is slightly less than 1:1 waste to treated. It has made somewhere between 7500 and 9000 gallons since new and still turning out 99.4% rejection rate or removal efficiency RO only water which is between 2 and 3 TDS down from the original 550-600. The first DI cartridge lasts over 1000 gallons, the second around 3000 gallons and the sediment and carbon block filters go 18-24 months between changes.

Where Vertex and others missed the mark was they do not use RO/DI to flush the system, instead using tap water which contains the very TDS they are trying to flush out. Unfortunately those in the industry who have been around very long know this will only work for so long before something has to give and be replaced.

You can use the parts you already have and improve upon the Vertex design by using the booster pump set at 80+/- psi and increasing the waste to the proper ratio for your water conditions.

ReeferBen · Feb 1, 2015

I did find out why I wasn't producing waste water, the flow restrictor was clogged. I cleaned it, it had some black grainy crap in it. The waste and production water levels went back to normal but the TDS only dropped to 15 last night. Then this afternoon I checked it and it was 28. I did throw the DI cart on so I could make a W/C up and it reads 0 with the DI on. I will have to order a new handheld TDS meter, I owned one years ago but I am sure its lost in my buckets of old reef gear. When I get one and can test I'll post up the results. The reason I liked the vertex unit originally was the booster pump was automatic and since I use the unit to fill my top off container automatically it is convenient.