Understanding TDS Readings

Ok I understand a TDS is a great idea for your ro/di. So when ordering from bulk reef supply mew filters for my ro/di I bought the dual inline. Great I have it and going in it says the tap water is 65 and coming out its 0 like we want it at coming out. The point of this is I know 0 is best but what are safe if any numbers and how is this thing working? The directions are um non existant. haha Well anyway just looking to figure it out via the numbers.

 

I havero/di plus unit, the line coming in reads the tds after the filters but before ro, the reason for this is so you know when to change the filters, knowing the TDS before the filters isn't very helpful as it will just tell you what your water is.

but to answer your question I think a tds under 5 is ok but anything above that is time to change the filters(i believe).

 

So 5 is the magic number. Ok that I guess is what I was asking. I dont know what the number means. As I also did not know what is an acceptable number before change.

 

To be honest, there is no magic TDS number that is good or bad. It depends on what is making up that TDS.

What the number is, is the ppm of non water in the water. So a zero means less than .5ppm of other things in the water, while 5 means 5ppm of other things.

Now if all those other things are calcium a high tds would be fine, but if all the other things where copper 5 tds would be very bad.

If you have RO/DI I say change out your DI if your TDS goes above 3, if you just have an RO, change it when the percentage of TDS from tap to RO goes below 90%.

Kim

 

TDS means total dissolved solids the higher the number means that the ro membrane has to work harder. so basically the point of the pre filters before the ro membrane is to help the longevity of the membrane thats why you should test after the filters and before the membrane becasue it is allot more expensive to change the ro then it would be for the pre filters.
edit: kim beat me to it lol.

 

Makes perfect sence. Thanks for the helpfull info. I was trying to understand what just one number could mean. It makes sence to me know.

Mike

 

From my directions:
Sediment filter- Change when overall production slows
Carbon Filter- On average city water will allow 10 gallons per day for one year
DI filter- When TDS reaches 15ppm or if you have a color changing DI has gone from dark blue to black to a blonde rust color.
Membrane- Typically last 3-5 years typically changed for slow production or poor water quality.