RO/DI output slowed down

N

NeilPearson

New member
I used to fill my 7 gallon container in about an hour and a half. Today after 3 hours, I only got about half a gallon out of it.

Any ideas what could have happened? I haven't changed the setup at all. It's not because of cold water... it has been a little warmer than usually and the water in AZ is never cold anyway.

Thanks!
 
My RO unit recommends a micron and sediment filter change ~ every 6 months, or ~ 3700g of product water, or sooner if the unit loses flow. I also use a TDS meter to keep tabs on changes in product water purity.
 
I did a full change of everything about 4 months ago. Also I just noticed the waste water never turns off. Before once the good RO water was shut off, the waste water would stop... but not anymore.
 
There is probably something wrong with your autoshutoff valve. It is a device that when pressure builds up in the output line it shuts the waist line down two. It also contains the restricter for the waist line it could be causing your poor output problem too.

A new one shouldn't be too much.

Whiskey
 
<a href=showthread.php?s=&postid=7175935#post7175935 target=_blank>Originally posted</a> by Wiskey
There is probably something wrong with your autoshutoff valve. It is a device that when pressure builds up in the output line it shuts the waist line down two. It also contains the restricter for the waist line it could be causing your poor output problem too.

A new one shouldn't be too much.

Whiskey
Click to expand...

I don't know if the output line ever builds up enough pressure to shut off the autoshutoff
 
My autoshutoff went bad recently and once I replaced it things were back to normal, well as normal as water in Phoenix can be anyway! Make sure you get a check valve along with the autoshutoff valve.
Neil, what do you use to shut it off? If its a float valve, pressure tank or ball valve on the outlet you are fine. Something has to stop product flow or an autoshutoff will never shut off....... Say that three times real fast!
 
<a href=showthread.php?s=&postid=7176143#post7176143 target=_blank>Originally posted</a> by AZDesertRat
My autoshutoff went bad recently and once I replaced it things were back to normal, well as normal as water in Phoenix can be anyway! Make sure you get a check valve along with the autoshutoff valve.
Neil, what do you use to shut it off? If its a float valve, pressure tank or ball valve on the outlet you are fine. Something has to stop product flow or an autoshutoff will never shut off....... Say that three times real fast!
Click to expand...

I have a ball valve on the output line. Even if I disconnect the output from the autoshutoff, it still just drips coming directly out of the RO unit.

About 4 months ago I got a new RO membrane. I went from the 90% one to the 98% one... at that time I didn't get a new flow restrictor. Could this have damaged it?
 
So you went from a 100 gpd down to a 75 gpd? If so, you likely didn't ruin the membrane by not changing flow restrictors, but you are letting too much water (and pressure) go down the drain - with the correct flow restrictor some of this water should be going through the membrane.

What is your waste to permeate ratio?

Blue
 
Using the 100 GPD flow restrictor is OK in our area with high TDS. It just makes yor waste ratio closer to 6:1 which keeps the membrane well flushed. Try opening up the RO housing, remove and inspect the membrane and o rings and reseat it in the down housing all the way tightly.
 
I am not sure what the ratio is. The waste water is a steady flow and the good water just drips... there used to be a fairly steady flow on the good water. I have a water softener on all the water to the house before it hits my RO/DI.

Yes I switched from the 100 gpd to a 75 gpd (mostly just to save my DI)
 
<a href=showthread.php?s=&postid=7181049#post7181049 target=_blank>Originally posted</a> by Unresistible Blue
The most common cause of the situation you describe is a clogged prefilter(s).

Blue
Click to expand...

I have good flow coming out of the prefilters though
 
I don't know the pressure I don't have a pressure gauge.

I took apart the autoshutoff and one of the little rubber disk things was kind of pushed in / folded. I unfolded it and put it back together. My RO is flowing properly now and the TDS of the RO dropped from about 150 to 45 (900 source water)

However, when I turn the ball value off (after the DI), the waste water still doesn't shut off. But considering the first problem was the autoshutoff, I am pretty sure this problem is related to the same thing... so I guess I need to order a new one :)

Thanks!
 
:)

:)

The main issue with under restricting the membrane in a low pressure app is that as the membrane gets older it begins to slowly build up blockage within the layers which increases the resistance for the water to pass through. By using a flow restrictor that is too large you are allowing the path of least resistance to be very attractive for the water flow and it will slowly tip the scales and reduce the flow from the output. In your situation I would suggest a 400ml restrictor and a flush kit of some type. Adding the 400ml restrictor should be a quick push on the membrane and loosen some of the obstruction. The flush kit will help you keep it out :)
Also due to the new variable in pressure this is likely the cause of the ASO failing.
Good luck!
 
<a href=showthread.php?s=&postid=7192860#post7192860 target=_blank>Originally posted</a> by NeilPearson
But considering the first problem was the autoshutoff, I am pretty sure this problem is related to the same thing... so I guess I need to order a new one :)

Thanks!
Click to expand...

There has been at least a batch of shut off valves that came from a single large manufacturer (that shall go un-named) that have been less than impressive in their performance. Not sure of the specifics of your case but this may figure into your situation too.
 
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