Just realized my DI system hasn't been working...

[Pbrown3701]

So i just replaced my DI cartridge as the color change had not progressed in some time. My TDS meter was also reading about 35. I figured the TDS meter was just bad as it's kind of old... Anyway, so i put in the new cartridge and TDS reads 0 again. I think i may have had the old cartridge in upside down so it wasn't working properly. It's been like that for probablly 5 months or so...

What types of goodies typically get through a TFC membrane that the DI would normally take out? Just wondering what I've been putting in my tank for the last half year...

[sidd129]

You were getting 35 out of the di? What is your tap water tds and also your tds out of your membrane?

[Pbrown3701]

tap water TDS runs about 300-350.
I've never measured the RO output, but would assume that the 35ppm reading is what it would be as i don't think the old DI cartridge was working. It's all fixed now but i'm just wondering what types of impurities i have been passing

[RandyStacyE]

I think that I have approx the same TDS in my tap water. I have well water. I don't even use DI anymore because my RO comes out 0-1 ppm.

Pbrown3701, I'm sure more experienced people will give you some excellent advice. It just sounds to me like there's a problem with the RO not the DI.

Are your prefilters still good? Do you typically flush the membrane and how old is the membrane?

[Pbrown3701]

i replace the membranes every 2-3 months because my city thinks it's cute to dump Alum in the water. My prefilters and carbon get replaced monthly when they get coated with thick yellow slime (alum). Over about a 3 month period, my membrane slows to a drip and then stops completely. I just replaced all prefilters and the membrane with this most recent DI switch - so i guess technically the problem could have been fixed elsewhere.

I just suspect the old DI because it changed rapidly for the first 6 months or so (about half way) but then stopped changing colors. Pretty sure I had it in upside down....and it wasn't the same on both ends...

[RandyStacyE]

I imagine that it would be worth while to rig up a flush for your membrane because of the gunk your city puts in the water. It might help to keep your membrane from fowling as long as you flush often.

I know that your DI will last longer if your ppm is lower pre-DI. If your DI is seeing a higher ppm it will extinguish sooner of course.

If this gunk is in your water do you think that using more prefilters could help? Perhaps a coarse one - a finer one- and a VERY fine one used inline before your carbon.

Since you're purchasing membranes so often ... maybe setting up your RO unit to run with 2 membranes would be a good idea. You would be making twice the amount of water with the same amount of waste water as you are with only one membrane. It could only help I imagine.

I use 2 membranes and since then I'll never switch back to 1.

[Pbrown3701]

I have a flush...it doesn't really make much of a difference.

I've also added an extra 5mc prefilter - helped a little, but only extended by about 2 weeks.

My feeling about adding another membrane is that i would just have to replace 2 membranes every time rather than 1. Sure, i'd get up to twice as much water out of them, but i'd also have to pay twice as much each time....so there's really no difference.

I've already learned to deal with my misfortune when it comes to RO membranes. It's the most expensive part of the hobby for me. We're moving in a year and a half back to Texas, so hopefully we'll get some better water...

[stugray]

Ha....

Sorry to tell you this, but... I live in Longmont Colorado.

TDS ( tap water ) into RO/DI = 35-42
RO/DI out = 0

I have not replaced my DI resin in over two years. I replaced my RO membrane once because I didnt have a TDS meter. Now I have the in/out TDS meter so I wont need to blindly replace it again.

The utility company tells us that we have some of the cleanest water in the country. It's nice to live uphill from everyone else ;-)

Stu

[sidd129]

Stugray wow That's awsome