Harry, my 46g tank is very similar to yours except I have laterite and root
tabs in sand instead of flourite. I have had excellent results by just dosing
about .5ml Flourish/week. For the last month or so I've been dosing .5ml
Flourish Excel/day as well. My faster growing plants have shown some
improvement (bigger leaves, a little faster growing) with the Excel. With only
1.5wpg light I can't keep red plants except for Red tiger lotus. Just make
sure that the light you use puts out the best wave lengths - blue and esp. red.

In article , "Harry Muscle"
writes:

I've been exploring the different Carbon suppliments for planted tanks
(Pressurized CO2 and DIY CO2). However, I just came across a product called
Flourish Excel made by Seachem. I did a little bit of research and the main
complaints about it were the cost, but from what I've calculated I can get a
2L bottle on EBay for 30US which according to the directions would last for
aproximately a year on a 40G tank. That ain't too pricey.

Now from what I've read it seems like the technology involved in maintaining
a planted tank is all goverend by how bright you want your lights (real
bright 2.5-4 wpg means you need CO2 no matter what, 1.5-2.5 wpg you can
probably get away with no CO2). I would probably go for something in the
mid range of complicated, meaning using lights about 1.5 wpg. So now onto
my question. Would this be a good combination:

40G tank
1.5 wpg of lights (60Watts)
Flourite soil
Use Flourish Excel instead of any CO2 injection

Does anyone else have such a size tank and use Excel on it? Does it work?

Thanks,
Harry