Snake plant I've been growing in water for over 2 decades having mold issues.

I've been carrying this mother in law's tongue with me for about 25 years, through two marriages, 8 moves. It's never been in dirt and thrived pretty well in low light conditions. It's been in the current glass vase with the same 6" of rocks for the last few years. It's generally submerged 2" past where the root area stops. I regularly take everything out and clean it, probably the last time was about two months ago.

Today I noticed at the water line level there was a film of mold on the vase and the leaves. I've gently washed off the plant as best as I can, and I'm bleaching the vase and rocks and will wash and rinse those a few times before putting it back together. I'm going to move it to somewhere with a bit more light although it's done just fine in far darker places than it is now. Just wondering if anybody had any tips, suggestions, or words of doom about how once this happens to a plant it's likely to slowly die a painful death!