New RO membrane not working?

[josh27]

I started getting 1/2 TDS out of my rodi so I bought all new filters. With all new filters except the ro my tds stayed the same so I replaced the membrane. After flushing the membrane for 15 minutes and running it for 4 hours its still making 10 TDS water. Did I get a bad membrane? MY tap water is around 250 TDS and my water pressure is 75 going into the unit.

 

[Buckeye Hydro]

Josh - From your post it looks like your not clear on when to replace which filter. You amy want to take a look at our No. 1 FAQ, here: http://www.buckeyehydro.com/faq/

Russ

 

[oldsalty]

RO Membrane

RO Membrane

I started getting 1/2 TDS out of my rodi so I bought all new filters. With all new filters except the ro my tds stayed the same so I replaced the membrane. After flushing the membrane for 15 minutes and running it for 4 hours its still making 10 TDS water. Did I get a bad membrane? MY tap water is around 250 TDS and my water pressure is 75 going into the unit.

Your filters have NOTHING to do with TDS. That's your membrane. 1/2 TDS is GREAT. Most membranes remove 90 to 95% of the bad stuff depending how bad the incoming water is. Your carbon filters keep the chlorine off the membrane which is DEADLY to it. Do you know about the DREADED TDS CREEP? When your RO unit is not running the bad stuff stays on the membrane. When you start up your unit, if you can measure the out going water that's being produced you will see a HIGH TDS for a couple of minuets until all that bad stuff is flushed off, then the TDS goes down to what it should be. If you use DI all that BAD water goes rite into your DI resin and uses it up quickly. You should flush the membrane for a couple of min until the TDS goes down to normal levels. When you start seeing high TDS coming out before it enters your DI (if you use one) after its been running for a while that indicates your membrane is beginning to clog up and should probably be replaced. I replace mine when the TDS reaches 25 or over

Good Luck
Kelly in San Antonio

 

[Opus123]

Your not clear on where your tds numbers are measured. Is the 1/2 and now 10 after the RO membrane or after the DI. With your 250 tds at the tap, an average ro membrane will give you around 12 tds and are really good ro membrane will be around 2 to 3.

 

[oldsalty]

Where to measure

Where to measure

Sorry, I forgot to mention that, TDS reading should ALWAYS be taken before the water enters the DI Cartridge. You need to plumb the output from the RO membrane so you can bypass the DI Cartridge temporary to give the system time to flush out the lines. This is best done by installing a 1/4 inch tee and a couple of 1/4 valves. Another thing you should really have in an in line TDS meter. This little guy has a switch on it that shows source TDS in one position and filtered water in the other. NO system should be without one. Look at Bulk Reef Supply, they have them.

 

[Buckeye Hydro]

You're referring to the old DM1 - the 2-probe inline TDS meter from HM Digital.
That's a good match for RO systems - that's what it was designed for.

A better match for RODI systems is the TRM1 - the only 3-probe inline TDS meter on the market. Buckeye introduced the TRM to the reefing world back in 2013. It allows you to monitor the feedwater, RO water, and DI water.

Russ

 

[Opus123]

So are we just talking to ourselves in this thread?

 

[Buckeye Hydro]

Its a small, elite group!

 

[oldsalty]

Yes that the one, I had not heard about the new one, however I quit using DI a long time ago because I felt is is a big waste of money. RO water is clean enough for my needs, Id rather spend my hard earned money on corals and fish. Heck some folks use regular tap water and have never had a problem with their reef tanks. Just wanted to pass on what TDS creep is cuz so many have never heard of it.

Kelly in San Antonio

 

[Johnseye]

I started getting 1/2 TDS out of my rodi so I bought all new filters. With all new filters except the ro my tds stayed the same so I replaced the membrane. After flushing the membrane for 15 minutes and running it for 4 hours its still making 10 TDS water. Did I get a bad membrane? MY tap water is around 250 TDS and my water pressure is 75 going into the unit.

There's a big performance difference between the different GPD membranes as well as the flow restrictors. Not sure if they will affect your TDS. I know I had problems with mine when I tried using a lower GPD membrane and different restrictor. My tap TDS is about the same as yours. The experts at Buckeye may be able to shine light on this.

 

[bif24701]

New RO membranes need time to fully wet. Also make sure you have the correct PSI.


Sent from my iPhone using Tapatalk

 

[Buckeye Hydro]

The key is to use a flow restrictor that yields something around a 4:1 ratio given your water pressure and water temperature.

 

[oldsalty]

Ditto here: If you try and put a flow restrictor designed for a 100 GPD membrane on a 75 GPD it will probably cause problems with the efficiency of the unit.

 

[Buckeye Hydro]

Yes - at typical pressures your waste water to purified water ratio would be well over 4:1