Hi and welcome to the forum. I'm pretty new myself but noticed you have about 15 watts of light in a 44 gallon tank. Even if it only has 35 gallons of water (assuming you are only using the one 15 watt t8 bulb) you have well under 1 watt per gallon of water. This link
says very little but algae grows in 1 watt per gallon. As an example my tank is close to yours in size, 47 gallons with a large rock mountain in the middle, and I have about 100 watts of light on it and looking to add more. If you want to add more light you can check out this link
for cheaper lights than what the fish store sells.
I would concentrate on the lighting section of the first link above before moving on to the substrate and fertilizer or co2. More light should get your plants in action!
Hope this helps.