I plan on discontinuing the aquarium water immediately. I just did a little experiment. I tested 4 pH sources just for reference to try and figure this out.
Aquarium water pH was 6.5
Tap Water was 8.2 or 8.3
Alfalfa meal brewed for 5 min brought pH from 8.2 to 6.4
Organic Tea ph is 5.8

My theory is that the alfalfa mixed in with coco as well is influencing pH and the organic tea is leaving deposits that are driving the soil pH down.
So maybe not radioactive soil after all:>
Please inform me if this is incorrect. My plan right now is to flush entire medium. Not sure if the recommended 5.8-6.2 for coco is the correct range to shoot for.
Thanks for ur help figuring this out