Ok. I added some plants to my pond (no fish yet) and I tested the PH and alkalinity and they are both high. What is the best way to lower PH and alkalinity. I know that once I get the ph where I want I can add cruched oyster shells to get it stabilized but how do i lower it? The PH is above 8.4. Is water changes the best way to go or is there something organic I can add? Any help would be great.