ro/di Help please

Ok with all this ro/di - tap water talk lately i decieded to test my ro unti. I got a digital tsd tester .My tap water going into the unit is 210 my problem is my water coming out of my 3 stage coralife unit is 95 ppm. NOT GOOD i know, I have replaced my cartridges about 3 months ago. Do i need to replace them again or is the membrane gone? Please help I really dont want to buy a new membrane but who said this is a cheap hobby thanks guys and girls!!

 

How old is the membrane? My guess is that it needs to be replaced, especially with that high of tds after going through the unit. The only other thing I can think of is that because it's only a 3 stage, it's not getting to 0 tds. What are the three stages?

 

What is the gallon per day out put and how old is the membrane? Is your water chlorinated or is it treated with chloramine?

 

Its village water so i really know nothing about the water. Its a 50 gpd unit. It has carbon -mixed resin-a pre filter . The membrane is prob 2 years old or so.

 

Membranes are really only good for a year--I would say that is where to start!!

 

To troubleshoot a RO/DI unit you need three TDS readings. Tap water, RO only before DI and final RO/DI.

All samples need to be directly from the unit, not a storage tank or through a final taste and odor carbon filter which I hope you don't have. Let the unit run for 10 minutes or so to make sure it is flushed and you are not reading TDS creep water.

Do it like this:
1. Using a squeaky clean clear glass drinking water glass which has been washed by hand, not a dishwasher, and has absolutely no water spots or soap residue, draw a glass of tap water and stick the meter in it. Let the reading stabilize for about a minute and record the reading.
2. Triple rinse the meter and the glass in DI water, in your case if the DI is suspect get a gallon of distilled water. You may want the distiled anyway to see if your meter will zero out to check calibration or condition. If the meter does not read close to 0 in distilled water I would say the meter is suspect too.
3. After triple rinsing in DI or distilled, draw a RO only sample straight from the RO membrane housing, disconnect the line leading to the DI and take it there. Again let the reading stabilize and write it down then triple rinse in DI or distilled again.
4. Draw a RO/DI sample straight from the DI filter, no storage or top off reservoirs. Let it stabilize and write it down. Do a final triple rinse and put the meter away capped and turn the glass upside down so it stays clean for next time.

What are the three TDS readings?

What is your water pressure?

What is your water temperature?

What is your waste ratio? It should be 4:1 waste to good, many people neglect to check this and it can kill a RO membrane in a heart beat.

Membranes should last about 3 years providing you keep the filters replaced with good quality replacements and you and you disinfect the system when you service it.
Prefilters and carbons last 6 months and DI is entirely dependent on how well the membane is working and how much you make.

 

Az desertrat thank you so much for your help. After thinking it over and doing some tests like you were talking about I found it was going to need a new mebrane and atleast a new di filter. So after looking online and doing some research i ordered a new unit for another 50.00. I got my old ro unit used so who really knows what the deal was with it and i have never checked my ppm before. Thanks for everyones help!!!!!

 

Hopefully you bought a much better unit like found here for $149 complete:
SpectraPure Customer Appreciation SALE! 20% - 50% off

Coralifes are very low end but you could even order a membrane abd replacement filters here and stil be better off.

Don't buy most ebay quality systems as they leave a lot to be desired and are not what is considered reef quality.