How many litres should my resin create 0tds?

Hi, guys, just wanted to confirm whether my virgin di-resin is lasting as long as it should.

i use the 100gpd ro system with 3 chambers, 1st being the filter to remove dirt rust ect, the 2nd being carbon block and the 3rd is the resin… tap water tds reading at start is 286ppm

the resin was normally purchased in a 650ml cartridge that i just changed over when reading went up. ive since purchased the 25L bag as a cost reducing measure.

but since changing to refilling the cartridge as apposed to changing them for a ready filled one i am under the impression the resin doesnt last as long before the tds reading creeps up,

so ive worked out that the post RO tds reading is around 25-30ppm. when cartridge is filled with 650ml of virgin resin it will produce 250L of 0ppm before stating to creep up again.

Does this sound about right to you guys

The system you mentioned (100gpd), is quite small and probably not that efficient, but my initial thought is that your RO is not producing very good water.

How old is the RO membrane?
What is the inlet pressure?

i have no idea of what the pressure is, just tap pressure, the ro system was bought new last december, i have only started using this method since then… u obviously don’t think this sytem is that effective before the di, but the time it takes is suitable for me as i work alone and am still building my round up, am currently using on average 400Litres a week, was working for a firm before i started on my own. tried to get as much info about the system before i started but fear it wasnt enough… i havent had a single complaint since. i got over the complaints while working for the firm so i can do the cleans good, but obviously the firm sorted the water out for me, i just turned up at the yard and refilled the barrels as and when i needed the water…

Here’s a chart you can use. This is based on 1 cubic ft of DI

TDS--------------gal / liters


I hope this helps you out…

There it is.

Thanks Shawn I was wondering about the size. Oh, and thanks for the chart Bill.

thanks you caught me before I edited my post:D

thats great bill, but as u will have noticed i use 650ml cartridges, anyone with maths skills who knows how many litres in a cubic ft lol.

just found a conversion calc online, 1 cubic ft = 28.31L

my di produces 250L at 0ppm, should be about 350L so 100L out

cheers bill

Remember not all TDS is the same. Water could have different solids that use DI faster, it all depends on the water were you are. The only way to tell what is in the water is with a water report, and that would only be good at that house. so the charts are just a guide line.