Anyway Eminor, its good that you are still looking into your CO2 as UKAPS says this is the cause of 90% of plant growth problems.
While measuring a 20ppm TDS increase every day with no obvious cause is an interesting mystery, it may not be the cause of your plant problems. Anyway, keep measuring to confirm whether its increasing by 20ppm everyday? (measure at the same time each day to eliminate any "CO2 effects" (if any))
While measuring a 20ppm TDS increase every day with no obvious cause is an interesting mystery, it may not be the cause of your plant problems. Anyway, keep measuring to confirm whether its increasing by 20ppm everyday? (measure at the same time each day to eliminate any "CO2 effects" (if any))