Leigh,

Thanks for your reply.

Yikes! That's too way too much light to have on a tank without CO2
injection.
You need to get your CO2 levels up.

That's what we're working on now with the DIY setup.

Relevant points. Yes it's a lot of light
I guess my casual response is that TMTOWTDI! When I had lower wattage
fixtures everyone here insisted that I needed MORE light! I certainly know
that you can have too much of a good thing, and that this light level is
rather high. I have/had been using Flourish Excel as a supplemental source
of carbon. I never took the time to set up the CO2 system although it was
rather easy to do. The tank did well with a different group of plants with
low light and no CO2--no surprise there.

The plants were growing well, as was the Egeria, without any CO2 addition
and with minimal additions of Excel. They grow/grew well for months. Algae
problems that were easily remedied came and went depending on changes in
fertilization. There's probably more algae there than you or some of the
crew would accept, but it's not much. Recently the algae problem was "fuzz"
that covered some leaves, a bit like razor stubble a few days old. This is
going away with the addition of more NO3. The snails are cleaning up as
well.

Almost all the plants were PEARLING without the addition of CO2. The high
light conditions no doubt had the plants sucking as much CO2 out of the
water as possible, possibly leaving very little.
Some of the plants might have the ability to use carbon from carbonate, as
some algae can. Tom or George mentioned this recently in another thread. I
can't speak to this issue in detail but the tank constantly needs the
addition of bicarbonate to maintain any measurable KH.

How long has this tank been set up with that lighting? And how do you
keep the
temperature at 74 degrees with that much light over the tank?

It's been at least 6 months. The room temp is 70 degrees F. The light is
separated from the tank by a 3/8" piece of glass, and the front and back of
the top of the tank are open along the length of the tank; 3/4" slits all
the way across, allowing heat to escape. It's not a closed hood. I just
checked the temp again and 4" deep into the tank it's showing 73 deg. I
guess there's just not that much of a heating effect with this setup.

The temp hasn't changed since that plant was introduced, so the original
question remains, why is the stuff rotting now?

Thanks again,

Lee