RO/DI Flush!!

[xpxdx]

My TDS has been like 3-4 lately, so I figured I'd check out the system and see what was up, since the DI section was only half depleted. Turns out the output of the RO had a TDS of 49!! My tap water is usually around 150, which is a terrible ratio.

I flushed the membrane by removing the flow regulator and letting it run for a few minutes. I tested some of that water, just to see the number, and it was in the 160's, higher than the tap, for a bit, then it went down again.

After I put it back together, the RO was down to 14, about right for a 90% membrane, and after the DI, zero again!!

:idea:

 

[johnd651]

how do you flush?

does it just use more pressure on the feed or do you reverse the feed and product/waste?

 

[Conesus_Kid]

I try to make it a habit to flush my RO for a couple of minutes every time I go to make water.


After reading this, I'll be sure to continue that habit!

 

[Jacwil]

Yea I picked up a unit for free from a member on here...it needed new everything but that was fine. Srixon, (Don), helped me got it up and running and installed a flush kit on it. Our nasty village water is at 650TDS and I'm at 001 product going out. I flush for 10-15 secs at least once a day.

 

[Capt_Cully]

I try to make it a habit to flush my RO for a couple of minutes every time I go to make water.


After reading this, I'll be sure to continue that habit!

On your advice Scott, I added a flush kit from Bulk Reef Supply for like $10. I flush for about 15 minutes every time I make water. Seems to be doing the trick so far. Prior to adding it, my TDS was running 2-3. Now, 0.

 

[Capt_Cully]

how do you flush?

does it just use more pressure on the feed or do you reverse the feed and product/waste?

Be sure to watch the Vid.

http://www.bulkreefsupply.com/store...ems/ro-di-accessories/membrane-flush-kit.html

 

[johnd651]

thanks for the link.

i actually looked into the RO/Di machine at work, to see how that works. i work in a chem lab, and the unit us fully automated, but i did find out that it flushes the membrane at least once every 24 hours, and during times of use once every 10 mins.

it has a sediment prefilter, carbon prefilter, 10% retention membrane, holding tank, high purity DI, low TOC Di, and then UV lamp. When you draw water, it has a splitter/diverter valve, so you only get about half of the water, and the other half goes back into the tank. because of the tank, it flushes even while you are drawing water off.

 

[Capt_Cully]

woah, that sounds nice!

 

[Gary Majchrzak]

flush often!

Additionally -for years it's been a noticeable trend around here that TDS in source water increases every winter.

Obviously, RO production slows in colder weather as well.

 

[ggdowski]

Our tap water in Mendon is only reading about 118ppm.
I guess I should be happy. The RO/DI unit pulls that right out.
I havent probably flushed as often as I should. But I do keep a close eye on the tdm numbers.

 

[sg1838]

Is there an acceptable TDS output other than 0? My one filter (sediment?) has turned mostly brown, and I am expecting that soon the TDS on the output side will start rising from 0. Is that when it's time to change the filter, or should I change it BEFORE I start to see a rise in the output TDS?

 

[johnd651]

im not sure what is and isnt acceptable, hopefully someone else can chime in on this

but the unit at work is running at 0.0027 ppm and this is the water we use for all out reactions.

 

[xpxdx]

My first filter gets brown pretty quick, and the 2nd one gets slightly brown, i don't think it effects the output much tho. You are supposed to replace the filters in front of the RO every 6 months, but i've been doing it like once a year or so.

The output of the RO section should be about 10% of your tap water, and the DI should take care of the rest.

I don't think hobby level TDS meters are super accurate, but 0 is obviously best, single digits aren't a huge problem. i'm not sure if there is a definite cut off point where you would never want to put the water in your tank...

couple of scientific-ish articles from randy holmes-farley:

http://www.reefkeeping.com/issues/2004-04/rhf/feature/index.php
http://reefkeeping.com/issues/2005-05/rhf/index.php