TDS Reading

[coralGoodie]

I just got my new TDS that I bought from EBAY. I checked my tap water and RODI water. My tap water's reading is 180 ppm and my RODI is 110ppm. Is my RODI reading really bad? I have ordered the membranes from Sir, Water & Ice just to make sure.

What is the ideal TDS reading on RODI? How often should I change the membranes?

 

[pookstreet]

You should have 0 after your DI. RO only should be in single digit or low teens at most. Sounds like you may have a bad RO membrane.

 

[coralGoodie]

<a href=showthread.php?s=&postid=7374566#post7374566 target=_blank>Originally posted</a> by pookstreet
You should have 0 after your DI. RO only should be in single digit or low teens at most. Sounds like you may have a bad RO membrane.

Is this bad for my reef tank? The memebranes are about 15 months old. I've already ordered a set .

 

[loc01]

What is the acceptable range on the reading?

Thanks,
Loc

 

[seamist]

my tap water was around 400, my Ro/Di into reef tank was around 10-12, my drinking water from the refigerator / icemaker was around 360..LOL

 

[bromion]

I had similar problems at first. Things to check:
What is the TDS reading from the RO membrane only, before the DI? It should be below 20 at worst. If it's not, try flushing the membrane. You can do that on some systems that have a variable flow restrictor by opening the valve, or by removing the flow restrictor that's on the RO part if it's not variable. You should flush the membrane every few weeks for 1/2 hour to keep it in shape.

If the TDS on the RO is still high after flushing for 1/2 to 1 hour, then you probably need a new one. I think they ought to be replaced every 1-3 years depending on conditions and use. You may need new DI resin, too. Luckily that is fairly cheap.

 

[ReefMeister2]

There's nothing wrong with the RO membrane, I can almost guarantee that. Readings that high indicate either something is hooked up wrong (waste/product water switched on accident) or the membrane housing is not sealing properly. You could try re-tightening, but I've seen bad membrane housings on a number of occasions that were defective and needed replacing.
This thread may help:
http://reefcentral.com/forums/showthread.php?s=&threadid=619925

 

[NicoleC]

What is the acceptable range on the reading?

With DI, the only acceptable reading is 0.

With RO only, anywhere from 1-5% is pretty normal and the low end should be the range you shoot for. Anything under about 20 is pretty good.

For example, my tap water is over 800ppm, but my RO only is 7ppm, or <1%, which is very, very good.