Old Happy Plants Are Dying

[webjen]

I am so depressed and frustrated and running out of ideas. I had a 65-gallon with beuatiful plants; blue temple, anubias, crptyo, rotala indica. it was all spreading like crazy, growing so tall i had to keep pruning it. I've had many of these plants for 10 years or more. Around 4 months ago, I figured it was about time to change my bulbs. At the time, I couldn't find 4 of the the 6700K i had been using, and substituted 2 of the 4 for 10000K bulbs. After a little bit, it thought the leaves were getting burnt, they seemed to be losing their green flesh and turning a gray/brown. I sought out the 6700K bulbs, got rid of the 10000K, and waited. I'm still waiting. It's been 3 months since I put the right blubs all back in, and the plants have never recovered. They're mostly low-light plants, so don't know that's it, but it's all that changed from the last couple years. Some of the leaves get yellow, most just get mushy or holes in them. I've tried potassium, which i have NEVER used in 10 years, so I can't imagine it's that. I've always used the Flourish series of Flourish, Iron, and Excel, that hasn't changed. I even tried using a little tap water with my water changes (always use R.O., always have without issue) to see if some trace minerals were needed. My substrate is littered with dying mushy leaves. I don't know what to do. One corner of the tank seems to be OK with new growth, the bulk of it is a disaster. I don't know if the bright light shocked them too the point of no return, or since they're older, they couldn't recover? I am heartbroken when I look at pictures of my tank from months ago. It was so pretty back then! appreciate any thoughts...i'll try to post pics later