TDS Meter Replacing

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david540i

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I was just wondering at what point do you replace your filters in your RO/DI unit.

I just changed mine out and its reading IN 175ish OUT 35

Is that ok?
 
Where are you taking the readings. If the 35 if the final product something is not working right. You should get around a zero reading if it is after the DI resin unit. 35 may be high for after the membrane too. You should be getting 95%+ rejection with a good membrane. Check your installation. :)
 
How long do you let it run before testing it? Are you collecting a water sample in a clean cup, or measuring the water in a larger collection vessel?
 
My TDS is measured IN inline where the water comes in from the washers cold input, then the OUT is after the DI resin right before it hits my storage jug.

Could it be something I did wrong?
 
How long did you let it run before you tested?
 
I let it run for a good 3 or 4 gallons, dump it and then measure. I have let the media set for a bit cause the TDS was bothering me
 
Did you replace the ro membrane? If you did you may need to try a re-installation. Sometimes it doesn't seat properly.
 
You said filters. What about the DI cartridge or resin ( if you have a refillable one )? If you just changed filters but not the DI, you could get reading like that.
 
Your right, i have not replaced the Di resin. Are those readings ok to place in a reef tank?

At which point do you replace your resin/filters on the TDS?
 
Isn't the 35 a little high? I used to get around 10 out of mine with no resin and that was with a reading of around 250 out of the tap.
 
at my work we have a huge massive gargantous you get the point ro system. It is a 6 stage regenerative unit. The in tds is 450ppm (garland water) and the out is 7.5ppm. It doesnt have a di unit but at 7.5 and free I use it anyways. I was thinking of buying a di cartridge and hooing it up to hoses then hooking up to the output for on the fly use. But to answer the original question 35 is high for RO only so i would say you need a new membrane or backflush and new DI resin. BTW i tested some LFS water and it ran 15-20ppm. Not too good especially if you are paying for it.
 
Great guys. thanks for the info. With my first set they where right around 5ppm then when I changed the filters, they went UP! Sometimes gotta be wrong, I'll tear into it and replace what i can.

John, I'll have to take mine apart and see thats goin on with it. Thanks for the offer, I'll let you know how it goes.
 
I was getting a reading of about 8-12. I changed the resin in mine and it now reads....either 1 or 0 (if I let it run for a minute or so). The change in resin (if your system permits it) makes ALL the difference in the world. PLUS, the resin is NOT that expensive...IMOP.
 
No, the DI resin if you have a DI unit on yours. If not you might want to get a DI unit to polish the water. You can get them on ebay or Marc may sell them. :)
 
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