Thnx for the response & I'll agree w/ everything you said Hermie, however, my specific problem is that pH is rising too rapidly with nothing but RO water and Cal Mag Plus in the reservoir.

I have just lowered the concentration of Cal Mag Plus to 2.5 ml/gallon at the recommendation of Botanicare tech support and will see if this will stabilize the pH.

On a separate note does anyone know if it's possible to grow a seedling using only RO water with nothing added?

Thanks
fulltilt Reviewed by fulltilt on . RO H20 + Cal Mag Plus = Unstable pH Hello farmers having some pH problems. Here's the setup... 20 gallon tote with 6 airstones for a bubbling DWC for seedlings. Inside the 20 gallon tote there is currently 15 gallons RO H20 w/ 75 mL of Cal Mag Plus (5 mL per gallon Cal Mag Plus). There is nothing else in this reservoir. Air temps are around 68 degrees farenheit and water temps are between 63 - 68 degrees farenheit. Rating: 5