Since I got my TDS meter, I started flushing out pots with distilled water.
Many pots were showing initial TDS readings of 50-80 ppm in the initial flushout water. *I kept flushing until the reading was below 35 ppm.
Some new soil I mixed is troublesome. *Many plants have not done well in it, and a few have died.
When I checked the TDS reading from these pots, it was ~200 ppm!
These pots were filled with peat that (for the first time) I had rinsed well (with rainwater), and mixed with sandbox sand. *It took a long time for the readings to drop, and once they did, I found if i rinsed a day later, the readings were very high, again.
What's the deal? Maybe the sand is not pure quartz, and is leaching in the acidic peat?