Hi Matt, I add Baking Soda (NaHCO3) routinely because it seems to help my plant growth. I try to get in the 3.0 - 4.0 dKH range but if I forget to add NaHCO3 when doing a water change the KH drops. Here is where I go to compute how much Baking Soda to add to raise my KH a certain amount based on the gallons of water in the tank (not tank size). Typically if a lot needs to be added I do it gradually over a couple days or so. http://www.dataguru.org/misc/aquarium/CalKH.asp?Gallons=35&KH=3&measure=0&Ba king+Soda+%28Teaspoons%29=2.69&SKH=&EKH=&pHChange=0.00 Roy _______________________________________________ GSAS-Member mailing list GSAS-Member@thekrib.com http://lists.thekrib.com/mailman/listinfo/gsas-member