Congrats! You're getting some really healthy growth in there. The interaction between your cats and fish sounds funny. As far as carpeting goes, do you think it's due to the depth of the tank? The last picture you posted gives some perspective on how fast light dissipates. You can really tell the difference between the top third, and the rest. I had the same problem trying to grow stems in a 55gallon. I don't know
just a thought.