Aquaponics question from Haiti

Aquaponics - Oct2015
We live in the Arbonite Valley and are trying our hand at Aquaponics with talapia and different plants up top. So far, we have found that our PH levels are through the roof. Any idea how we can get these down? Our medium to grow the plants in is rocks and we are wondering if maybe they are the reason the PH levels won’t come down.

It very well could be the rock or if the system is not well established it could just be a temporary spike until the nitrogen cycle becomes stable. Carbon dioxide and fish waste lower the PH you could try adding aeration to help lower it. Usually even the most porous rock will only leach to an established point have you tested your source water?

It’s been a while since a reply, wondering if you have had any luck? I’m curious is you could offer a pH range you are observing. We had an aquaponics system in Titanyen for a few years, and our pH levels were typically in the low 8 range. Our water had rather high alkalinity, so I would second that idea of looking at your source water. Strangely enough, even when we added water that had been acidified to mid 6’s, the system pH would tail back up over 8 during the course of a week or two. We never quite understood why.