Light is usually the issue with plants. The majority of plants will grow fine provided they have good light, meaning sufficient intensity and spectrum, plus of course duration which should be determined solely upon nutrients.
Re the watts, all T8 (the regular) fluorescent tubes come in standard wattages for the length of tube. For instance, a 48-inch tube is 40 watts. However, some manufacturers have tubes that use less power (watts is simply the unit of energy required by the tube to light) and produce the same intensity, example 32 watt 48-inch tubes. So you cannot buy different wattages for the length of tube. Hope that makes sense.
So your 24-inch T8 tube will be a standard wattage, usually 20w. Some manufacturers may make tubes that produce the same intensity with less energy, but once you select the type of tube it will come in the one wattage for the length. The Floramax is 17w, so there will not be a Floramax with higher watts in a 24-inch length. However, a single tube is sufficient for most plants.
The type of tube is critical. Various tubes will produce different intensity and colour/spectrum of light, according to the phosphors inside the tube. To take an example from the Hagen series "...Glo", there is the Aqua-Glo that is primarily red and blue spectrum but the intensity is quite low. Then there is the Life-Glo that is red, blue and green and the intensity is double that of the Aqua-Glo. Both tubes will be 20w for a 24-inch. But the Life-Glo will produce double the light intensity, and the spectrum will be different. It is closest to the sun at mid-day, so the colour rendition of fish and plants will be true.
I've not used the Aqueon tube myself, but the spectrum chart (attached below) suggests it should be fairly balanced light. It has peaks in the red, blue and green. The spectrum for the ZooMed UltraSun is also attached for comparison. I would have to actually see the Floramax over an aquarium before I could comment further because the way the phosphors are used in the tubes can affect the colour, and of course there is also the intensity which is not mentioned on their website.
If you are minded to try something else, two tubes that I have used and can recommend are the ZooMed UltraSun that another member mentioned earlier, and the very similar Hagen Life-Glo 2. These are good spectrum, about the best actually, and good intensity.
To the fertilizer: Many nutrients occur naturally from fish food, waste (organics broken down by bacteria in the substrate) and tap water (replenished at each water change). I've not myself used Nutrafin liquid, but the ingredients look pretty good and i know others in the past have had reasonable success with this product, so once a week should be sufficient. Seachem's Flourish Comprehensive Supplement is the one I use, as it has all nutrients (except oxygen, carbon and hydrogen) so when your Nutrafin is gone you might want to try Flourish Comprehensive.
Don't expect "miracles" quickly. Plants grow according to the balance of light and nutrients. The rate of growth largely depends upon the degree to which nutrients and light are balanced and the quantity. Once any nutrient is un available, or if the light is not sufficient in intensity and spectrum, the plants will slow and possibly stop growing; they won't die, they just can't photosynthesize (grow) further if something is missing. Most of us here have basically natural or low-tech systems. We have (or should have) good plant growth, but slow. But healthy, thriving plants that grow slow are still healthy, thriving plants.