Like everybody else, I've read this in many many places too. I got a
reddish/purplish plant and it died in my low-light tank within a couple
weeks.

At low light, the effect of CO2 are still great, yet many do not use
it. The lower light slows the growth down a considerable amount while
still maintaining health. While people hear that low light tanks do
not need CO2, they still reap the same great benefits from CO2
additions, something I suggested about a year prior to Tropica. Then I
mentioned that the clear hard water springs in Florida had the best
plant growth in natural systems, not soft water, Claus also show the
same thing in the Mato Grosso, which have identical spring types but
different fish.

The effect is maintaining good CO2 and nutrients and maintenance,
while lowering the light. It takes more than just light to drive plant
growth.
This maximizes the light usage by the plants.
This method shows the max and min levels of light that will produce
good plant growth.

Swords have always done extremely well at 1.5-2w/gal, D diandra has
been grown to very high levels at this range also.
Red Cabomba, Glossostigma etc....

My point is that the plants could have died, not done well for reasons
other than low light. Even proper trimming/over shadowing etc can
cause some plants to not grow well besi9de just the light/CO2 and
nutrient issues alone, there are other factors that are hard to
address unless the person mentions it or you can see their set up in
person.

Unless you address the other parameters that influence growth and
consider them and test for them, you do not know.......you are are
guessing and assuming.

That will cause you to believe that correlation = causation.
That is a huge myth factory that serves to confuse, exacerbate and
muddle plant growth issues with planted tanks. Isolate, go down one by
one to improve your plant growth......this will help you to become a
much better grower even if simply adding another lamp on solves your
immediate problem.

The total effect is the sum of the best levels for CO2, NO3,K,GH, fish
load, mainteance routines/water changes etc.

Yes, you can get away with not doing a couple of things, but if you do
them, the tank will be that much more stable and you can always
improve the growth some generally.

If you cannot improve growth or think you have no room left for that,
then you should be able to produce any design you have in mind with
any plant etc.
If you are having issues, then you can improve the method.

Regards,
Tom Barr






Regards,
Tom Barr