How much TDS do you allow?

scottyboys

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Water coming out of the sink 356, out of the filtered fridge 355, out of the RODI mighty might 007. When do you like to replace the filters on your RODI unit? When you get above 000?
 
most of the time i change it well before it even gets to 1 but every now and then if i have a heavy water month it will make it to 1 or 2.

it is cheap enough to change so there really is no reason to have any .
 
most of the time i change it well before it even gets to 1 but every now and then if i have a heavy water month it will make it to 1 or 2.

it is cheap enough to change so there really is no reason to have any .

I agree 0 is best I change when goes to 1
 
I try to go for zero, but sometimes I do use it when it reads 1
 
Im lame... below 10 is good for me.

350's is scary... tap here is running around 140 tds.
I think the government limit is like 400 or 500 for it to even be safe to drink. (don't quote me on that)
 
My tap runs 187 or so after my prefilter and carbon. No wonder I go through filters so dang fast!!!
 
I don't check as often as I should but I shoot for 5 or less. I have seen 10 and not noticed any problems. :ops:
 
As soon as I get 001....DI gets changed.

I have a well that goes through a good water conditioner. After the water gets through both pre-filters and the RO membranes..it's normally 002-004
 
I agree. I dont let it go above 10. Usually I change the DI resin at about 8.


Im lame... below 10 is good for me.

350's is scary... tap here is running around 140 tds.
I think the government limit is like 400 or 500 for it to even be safe to drink. (don't quote me on that)
 
Im lame... below 10 is good for me.

350's is scary... tap here is running around 140 tds.
I think the government limit is like 400 or 500 for it to even be safe to drink. (don't quote me on that)
Below 10 for me as well. Tap reads around 430, if I changed it when it reached 1, I'd have to do it 4 times a year.:squigglemouth:
 
Anything other than 0 is not good! The reason is DI resin starts to release weakly ionized substances even BEFORE it is exhausted. That means things like nitrates, phosphates and silicates are being released back into the treated water even before you can read them with a hobbyist grade TDS meter. Not good!

When I first start seeing signs of anything other than 0 I change resin immediately to prevent this. 10 is way way past time to change resin. What happens is once the DI is nearing exhaustion it loses its cation and anion electrical properties so all the things that have been adhering to the resin beads start dumping in very large quantities, much higher than your tap water levels since it has been accumulating on the resin for dozens or hundreds of gallons and concentrating. Don't wait, change it now!
 
Final TDS has absolutely nothing to do with the prefilter and carbon and should not be used to judge filter condition. Final TDS is a direct result of the RO membrane performance and DI performance, the others are just there to protect the membrane which in turn protects the DI resin.

Prefilters and carbons remove TSS or Total Suspended Solids, big stuff like sediment, particulates and colloidal materials, and VOCs like chlorine not TDS or Total Dissolved Solids, small atomic level things actually dissolved in the liquid which is what the RO membrane and DI take care of. Suspendeds and Dissolveds are two different things treated and monitored in two different ways.

You change prefilters and carbons on a 6 month schedule like clockwork or when a low level chlorine test kit tells you you have chlorine breakthru and an inline pressure gauge tells you you have a large pressure drop, one or the other or both. The easiest way is every 6 months by far.

You change DI resin when you start to see TDS breakthru. You change the RO membrane when it is no longer producing a 94-98% reduction in incoming TDS or rejection rate or when the cost of DI replacements starts eating you out of house and home! Again the pre and carbon have very little to absolutely no effect on TDS.

Always remember to disinfect the system while you have it down to reduce or eliminate the possibility of virus or bacteria growth inside the unit. It only takes about 5 minutes and could be a lifesaver!
 

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