Would seachem excel and seachem root tabs be better or a mini pressurized co2 kit? This is assuming the substrate is just plain old aquarium sand.
Also, how many pounds would I need of the aformentioned sand per gallon in a planted tank?
Thanks in advance!
Some of what I will now mention has already been said, so bear with the repeat. But I would like to stress the all-important aspect of
balance. Unless this is understood and achieved, the planted aquarium will not be at its best, whatever the method. I don't know your particular level of experience, so some of this may be "old news," but it is at the crux of a healthy planted tank.
Aquarium plants require light of sufficient intensity to drive photosynthesis [this varies with the plant species]. But sufficient nutrients, of which there are 17, must also be available. Plants will only photosynthesize (= grow) up to the point at which something is no longer available/sufficient, what we call the limiting factor. This balance is crucial not only for plant growth, but with respect to algae.
Light we can easily provide, so I'll move on to nutrients which are the basis of your question. Most nutrients will be naturally present in a fish tank. They occur from fish foods and water changes. Some may not be in sufficient quantity, so we add them. Carbon is a macro-nutrient, but there is more of it available in a balanced system than many realize. But the question one must first decide, is the sort of "planted tank" you want. Different species of pants have differing nutrient requirements (with respect to volume) same as light. A tank full of stem plants and floating plants--all being much faster growing--will require more light intensity and more nutrients to balance. While a tank of ferns, mosses, crypts, Anubias and some swords will need much less of both.
Adding CO2 is not necessary unless you are aiming for a high-tech high-plant volume tank. The photo below is just one of my tanks, none of which use any form of carbon supplementation; but the plants are all low and moderate light requirement, and the natural CO2 is sufficient to balance.
If you feel the need to add carbon, I would do so with a diffuser and not rely on liquid carbon supplements like Excel. These will decimate some plant species, and if overdosed can kill plants, fish and bacteria.
Substrate tabs will benefit substrate-rooted plants (only), but this is not always needed either. Large swords, tiger lotus, aponogeton, etc which are fairly heavy feeding plants will benefit from substrate tabs. But they also must have liquid fertilizer, as must all plants if nutrient supplementation is needed at all. Some nutrients are only taken up via the leaves from the water column, so substrate nutrients are ineffective here. A comprehensive (complete) liquid supplement is the first thing to add, and may be all you need. The tank in the photo has plain sand substrate, with substrate tabs only next to the larger swords, and receives liquid fertilized (Flourish Comprehensive) once a week, and Flourish Trace once a week. I also use Equilibrium to increase the "hard" minerals which are completely lacking in my very soft tap water. But each aquarium is or can be different, depending upon your source water, fish stocking, and fish foods.
As to the amount of sand, you want somewhere between 1 inch and 3 inches, depending upon the plants. The tank in the photo has 1 inch in front (or almost) and not quite 2 inches in back.
Byron.