TDS is cool but isn't standard like EC. You'll be able to measure your solutions just fine but your readings may compare differently than other growers' mfg/model. Don't be alarmed if your full strength readings are several hundred points higher or lower than the next guy's TDS reading.
Is your res/plumbing new? Could be the cause of abnormal pH swings. A good wash with warm soapy water or a mild bleach solution might help.
I'd get some acidic base nutes to substitute for the pH down. I have 8.0 tap and lucas sinks it to less than 6. With your setup I wouldn't need much pH down, if any. Unless your res and/or plumbing have something to do with the rise.
Hope you get it worked out.
Is your res/plumbing new? Could be the cause of abnormal pH swings. A good wash with warm soapy water or a mild bleach solution might help.
I'd get some acidic base nutes to substitute for the pH down. I have 8.0 tap and lucas sinks it to less than 6. With your setup I wouldn't need much pH down, if any. Unless your res and/or plumbing have something to do with the rise.
Hope you get it worked out.