Why is RO drain pressure high after membrane?

[Jay Fortay]

Having some serious trouble here. I recently replaced my RO membrane and prefilters. A few days ago I checked my inline Tds meter and Tds were at 50ish. I then checked Tds after the membrane, before the DI and it was the same. At this point the flow out of what I thought was a defective 100gpd membrane was normal. I replaced the membrane with a new 75gpd which I believe was the original size to my Melevs reef unit. I ran the product water down the drain for a few hours and I was getting a TDS of 2ppm and the flow was normal. A couple hours later I went back to check TDS with the inline meter again and it was at 6ppm. I started investigating and found that water was rushing at much higher than normal pressure as long as the float was open. I pulled the drain line and the thing was nearly shooting water out. So I seem to have full water pressure with no restriction from the membrane itself. Any ideas? I've turned it off for now and will run it manually in the morning to top off. I may try refitting the old membrane to see if the new membrane is the problem. Thanks in advance for any insight you may have.

 

[Jay Fortay]

I do have the capillary flow restrict or installed that is original to the unit.

 

[Jay Fortay]

Replaced the new membrane with the old one. Pumps out 6ppm water way too quickly and is constantly draining way too quickly as well. ASOV maybe? Replaced it about a year ago...

 

[Jay Fortay]

Morning bump. This is seriously frustrating. To clarify I get what seems to be equal, unrestricted flow from my drain and product water lines. What gives?

 

[Tang Salad]

The capillary restrictors are for specific GPH, so you want to make sure you have the right on installed on the waste water output from the membrane. Based on your description, it sounds like that could be the issue.

 

[Buckeye Hydro]

Feel free to give us a call when you are in front of the system and we'll get everything squared away.

Russ
513-312-2343

 

[Jay Fortay]

Thank you Tang Salad and Russ.

Here is a synopsis of the problem that I posted elsewhere. I had a high tds reading (40ppm) about a week ago, I noticed that the filters that had been recently replaced were looking pretty bad as was the Di resin. I replaced the prefilters and membrane and still got tds. I took the unit to a local water shop and we found that the housing was cracked on the inside where the or rings in the membrane seat. TDS problem solved. I noticed then that the waste water was draining constantly. First it seemed like the ASOV. Replaced that, no luck other than it would intermittently stop the flow. Then I replaced the check valve, still no luck. I am running out of ideas. I have followed all the steps on your FAQs and done a ton of searching on the forums. To no avail. I've not found anyone to still have the constant draining problem after taking all of the steps detailed above. I don't know my incoming PSI, but feel that it probably hasn't changed since the system was running properly in the same location. Oh and, this wired observation may help. If I shut of the drain line manually and wait until I hear the unit turn off, when I open the drain back up it stays off until I open the permeate line again. I am 100% the ASOV is plumbed properly. Thanks in advance for any advice you may have.

 

[Buckeye Hydro]

When ASOV's don't work it is typically one or more of these four things:
1. ASOV plumbed wrong
2. Check valve bad
3. ASOV bad
4. Float valve not sealing 100%

You didn't mention anything about No. 4 above...

Russ

 

[Jay Fortay]

I have shut offs on my float lines. If I cut the permeate outflow completely, it still runs.

 

[Buckeye Hydro]

Feel free to give us a call when you are in front of the system and we'll get everything squared away.

Russ
513-312-2343

 

[Jay Fortay]

Thanks to Russ at Buckeye Hydro for giving me over a half an hour of his time on a Sunday! We got the drain to shut off. The DI needed "burped" which is where you open the DI canister just a bit while the permeate is running to allow trapped air to escape. It stopped the drain line. Now to address some other problems with my setup that Russ heard me identify. Thanks again Russ. I will certainly be ordering from you in the future!

 

[Buckeye Hydro]

I'm glad we got it squared away!

Emily