RO/DI working correctly? (1 Viewer)

[d00dy]

I have an Air Water & Ice Typhoon RO/DI unit. I have had it since day one about a 1.5-2 years ago. Originally when I purchased it, I would fill up a 35 gallon tub and keep it filled... After about a year or so the TDS started increasing.. When it reached 5-10 TDS I looked into replacing the filters (4 canisters). I replaced them all, and after a few months (maybe 2 at most) the TDS started to increase again. NOTE: I only have a 40 breeder and do 5 gallon water changes and 5 gallon top off (10 gallons each week). I then called AW&I and asked if this it normal, and the response was there is no way to know how long it will last because it is determined on the quality of the water going into it. I then purchased the 5lb DI refillable kit as suggested. I don't really measure how much water I fill, but it seems like I can get about 60 gallons MAYBE, before the TDS starts reading 1 and above. Is this normal? If so, why did the filters that came with the system last so long and this new stuff so short?

P.S. I do all the required flushing before each use and in between uses.

 

[steveb]

That seems way low. Almost like your RO membrane is shot, was it one of the four canisters you replaced? Does it have a pump to increase the pressure going into the RO membrane?

 

[d00dy]

No, I did not replace the membrane. I thought they usually last at least 3-5 years, and I have had this one barely 2 years. I guess it is worth a shot. There is no pump in the unit that I am aware of... It doesn't require power at all.

 

[steveb]

Do you know what your TDS is coming out of the RO membrane after it has been running for about 5 - 10 minutes? Mine is 7.

 

[tektite]

The sediment and carbon don't really do much at all for TDS, its the membrane and DI resin that handle that. If the TDS is rising after only that amount of water, I would assume your membrane is not working properly. Take a TDS reading right before the membrane then right after the membrane before the DI resin (after the unit has been running awhile to get a proper reading. Take those two numbers and you can get the rejection rate of the membrane. Most good membranes should be 98-99%.

 

[d00dy]

So what I found out is before the membrane it is 230, after the membrane it is 125...

 

[tektite]

Wow, that's really bad. A good working membrane should knock that down to 3-5. Replacing it should keep the DI going for a long time.

 

[steveb]

Yep I agree 100% bad membrane.

 

[d00dy]

I will order one tonight and hope it works . Thanks in advance.

 

[Buckeye Hydro]

doody - you got some good advice here from the resident MARSH experts!

Russ

 

[d00dy]

Yeah I agree, before I replaced the membrane my TDS was reading ~5. After the replacement, with everything else the same, it is now reading 0 again. Hopefully it will last a decent while this time. Thanks again.