A carbon block filter will make your water taste and smell better, but it will not help your TDS problem. My water has a similar TDS, and my RO system gets it down to 12-15. I bought a system from Airwaterice.com for $200 several years ago. It has 3 filters (10,5, and 1 micron) in front of the RO membrane. The line coming out from the membrane is split. One line goes to a 35 gallon rubbermaid garbage can which I use to store water for the orchids. The other line goes to a carbon block filter and then to a 2 gallon pressurize tank which we use for drinking water. The garbage can has a float valve (also available from above web site) which cuts off the water when it is full. The RO system has an automatic shut off valve as well. Ongoing costs are approx $20 each year to replace all the filters. The RO membrane should be good for several years as long as you replace the filters regularly. Mine is almost 3 years old and still delivering good performance (as measured by TDS). Replacement RO membranes cost $39. RO water is not really acidic, it is very near pH 7, but since it has no salts there is no buffering capacity and adding fertilizer drops the pH precipitously. I use MSU formula for RO water and add Pro-Tekt to raise the pH to near 7. The question is, how much water do you need each week? I use approx 70 gallons per week so it is well worth it.

mass, Why Reverse Osmosis? Why does Electrical conductivity have to be zero? Are you treating saline water? What chemicals does your City water test out with that makes you nervous and believe a reverse osmosis system is needed? Are you after better tasting water? The cost is high but the filters replacement frequency and cost is where they make their money(I bet it is hard to find that info). JMHO Aloha

Hey dude, thanks for the reply. I have exciting news! I checked just now and the bottom of the netpot on the tomato plant has tiny white roots poking out! Just 12 hours ago I poured plenty of EWC tea through the pot, maybe those microbes are helping things along. I suppose now I just gotta hope these roots don't get stunted and perhaps when they get long enough I won't have this leaf drying issue. :) I'm gonna go make some king crab legs now, time to celebrate!

Nice overview. I would also recommend BACI's hydroponic FAQs for more detailed information. These are available by doing a search in this forum for "FAQ".