Conductivity

[mordor]

I have bought conductivity meter recently. I measured conductivity of RO water I am buying from vending machine in grocery store and I am a little bit shocked. It has pH 6.7, conductivity 180 uS and TDS 90 ppm. I got same results with tap water from my Brita filter in my kitchen :x
I have not purchased RO unit because I have a small tanks and I need about 12 gallons per week for water change. I just wonder what are RO unit maintance costs per year. I may purchase SpectraPure 15gpd unit for aprox $100 so if I compare it to 12x52x0.25 = $156 spent on buying water last year it seems that I should think about it especially when I know that vending machines are not producing quality RO water.

 

[Z Man]

If your only going to use it for 12 gallon each week, those membranes will last a long time. I do anywhere from 25 to to 50 gallon each week and they lasted me a good 3 to 4 years before I needed new ones. That one in the store needs new membranes for sure. From the day you begin using it you will see the TDS start at 0 and every few month's you will notice it start to rise. I never change mine until the TDS hits around 20 or so as all I do is add less and less tap water to make the adjustment. My unit has one membrane & 2 filter cartriges. The new one's only have one filter and one membrane. I can't remember correctly but SpectaPure can tell you on the phone how much they would cost. I think I paid $9 ea for the filters and around $38 for the cartridge but you should ask before buying the unit. I have had my RO unit for about 8 years and changed them twice now. The last time was only a few months back.