Hi all,
"Flourish Excel" is 2.5% solution of glutaraldehyde (an "aqueous solution of polycycloglutaracetal" & "is a source of bioavailable organic carbon"), it is an intermediate in photosynthesis and it does work, but nobody knows exactly how. It is also quite toxic to fish and plants, (this is why it kills algae), if you use it at too high a level.
All my tanks are planted, but I would never use a liquid carbon supplement, CO2 or an EI type nutrient regime, yes they make you plants grow faster, and allow you to grow some basically terrestrial plants under-water, but there are drawbacks to all these approaches.
I want stability in my tanks above everything else, I want any changes that occur to occur slowly so that I can keep an eye on them and rectify them if necessary. If you are talking about systems with low nutrients, there isn't a vast amount that can go wrong, there just isn't the potential.
I use the car driving analogy, if you drive at 20 miles an hour you will always get to your destination, but usually a long time after somebody who has driven there at 80 mph. However every now and then the speeding driver will have a "crash" (like a CO2 dump killing all your fish), which could be very nasty indeed. Have a look here for details of the CO2/O2 interaction <
http://plecoplanet.com/?page_id=829>.
If you supply water, light and at least the minimum level of the nutrients required for plant growth, plants will grow. I'd suggest trying a few plants from the "low light list", most of these aren't really low light plants, it is just they can grow at low light levels and nutrient levels, and don't show much response to higher light or nutrients. Here is my
Apistogramma tank, reasonable light, no CO2 and a very lean fertiliser regime. Planting is mosses, ferns,
Cryptocoryne, Echinodorus and a some floaters (
Limnobium and Salvinia normally)
I think of this approach to planted tanks as the difference between growing Tomatoes and Orchids/Ferns/Alpines/Cacti etc., something like a
Phalaenopsis orchid will grow with very low nutrients, and die if exposed to very bright light or high nutrient levels. In comparison a Tomato plant will die if kept at low light and/or nutrient levels, but as long as it has enough water the more light and nutrients it gets, the more it will grow and the bigger crop of Tomatoes you will get.
In my tanks I want to grow Orchids, not Tomatoes.
cheers Darrel