I have a portable 340 gallon Cal Spa. I don't know the year or model. It came with the house in 2000. I suspect it's circa 1995.

I found water leaking through the cedar skirt in one of the back corners. I removed the wood and discovered some roots growing inside the insulation. Water was also seeping through the foam. I started pulling roots and foam out but I haven't found the source of the leak yet.

Can I rip away enough of the insulation to repair the pipes? Once I do, can I replace the insulation somehow?

I keep bromine in the water, shouldn't that have discouraged any roots from growing?

You'll have to keep digging until you find the leak. You can get some standard fiberglass wall insulation and hang on the inside of the skirt and that'll do a good job to replace the foam stuff. It'll also make it easier to work on it in the future.

Plants don't know anything about chemicals that are behind a pvc wall