I have had a barrel pond with a few gold fish for a few years and it has thrived. This year the water lettuce and hyacinths keep dying off. I have never had this problem and in fact in the past have had to throw away plants as they were overgrown. I started testing the water and the pH is 8. I have been using pH Down to trying to get it up around 7-7.5. It doesn’t want to budge. I did have a string algae problem and was able to rid the pond of it. I took the plants out of the pond and put them in another container to see if it was the high pH affecting them…no go. Any suggestion?? Heard about treating them with Miracle grow but not sure. Would appreciate any feedback.