Originally Posted by beastieseb187
Thanks everyone for your help - We're going to figure out a way to monitor the lighting situation!
Byron, thank you for your insight! It certainly helps a lot! I do have plant fertilizer in "substrate" and I also use API Leaf Zone as a fertilizer/plant food for my plants which I add once a week; the merchant at the store told me it was a good choice. What is your familiarty with CO2 cannisters and are they really much more beneficial than plant fertilizer?
First on the fertilizer. I consider API Leaf Zone as inadequate and would myself not use it. According to info on their website, it contains iron and potassium. Fine...but what about the other 13 mineral nutrients? True, some occur in fish food, some in tap water (depending upon the hardness) and some from organics; but it is unlikely they will all be there and in sufficient quantities. [And they also say that it is formulated for assimilation through plant leaves--but not all plants assimilate minerals through the leaves.]
Again, it's all about balance. Plants require 17 nutrients. Flourish is the only product to contain all of them [aside from oxygen, hydrogen and carbon which no plant fert contains]. Without the 17 nutrients, plants cannot photosynthesize fully, and this is where the light issue comes in.
Plants grow according to the "Liebig's law of minimum" that a botanist named Liebig formulated. It states that plants will grow up to the limiting factor--the point at which some nutrient or light is no longer available. In an aquarium, we aim to have light as the limiting factor, because light in excess of the available nutrients--all 17 of them--means algae has the advantage.
Now to CO2. Carbon is an essential macro-nutrient for plants. It is one of the 17 nutrients, so technically speaking it is not a substitute for fertilizer. In a "natural" or as some call it low-tech method, carbon occurs as CO2 from the fish and bacteria. In hard water with high carbonates some plants can assimilate carbon from bicarbonates--Vallisneria is particularly adept at this. But most aquarium plants come from soft water regions and their uptake of carbon via bicarbonates is limited; mosses cannot use it at all. But back to the CO2, there is a lot more of it in a healthy aquarium than many aquarists believe, certainly sufficient for good plant growth depending upon the number and species of plants. If you have a look at the photos under my "Aquariums" below my name on the left, you will see tanks that I have maintained for more than 15 years with no CO2 added. But the growth of those plants is steady but relatively slow. Pumping CO2 into the tank would increase the carbon, but remembering that bit about balance, you also need to increase the light and the other 16 nutrients. Otherwise the CO2 is basically wasted.
The type of "method" depends upon your expectations. If you want plants to grow and be healthy and contribute to the overall health of the aquarium and fish, the natural approach works fine. If you want rapid plant growth, flowering, etc., then you will probably have to increase all the nutrients and light. There has to be a balance no matter what the method. Takashi Amano has beautiful high-tech tanks; they have three times the light intensity I use, CO2 diffusion, and daily--yes, daily--injection of copious amounts of nutrients to balance. My natural method uses weekly Flourish doses and minimal light. The fish are happier with less light, the plants are growing, the tank is naturally balanced so it costs less--I'm happy with the result.