I think the T5's you have maybe to powerful for a low tech set up (especially with reflectors), without Co2 injection. With high lighting your plants will demand greater levels of Co2 and ferts. If you don't supply these elements your plants may suffer as a result.
Below is a quote from a great little article, which should explain a few things about balancing you tank (
The Balanced Planted Tank)
"Understanding the balance is the key to any planted tank. Any successful planted tank will be a balanced tank. These are a couple of things that the hobbyist often hears about, but many do not understand them or their implications. The purpose of this article is to introduce the reader to the balance, explain why it is important, and how to achieve this balance.
First, what does the balance consist of. The balance in question is the proper proportions of light, carbon dioxide, and nutrients. Plants require all three of these things in order to survive and grow. In order for the plants to take in the nutrients, there must be CO2 and light present. When any one of these three things is out of proportion there will be an outward sign to let the hobbyist know that something is not in balance. The amount of nutrients and CO2 required will be dictated by two things; lighting level and biomass of the plants, therefore, the appropriate levels for nutrients and CO2 will be different for every tank.
This brings us to point number two; why the balance is important. Plants, unlike algae, need CO2 in order to photosynthesise, without the presence of CO2, the plants cannot take in the nutrients and thus it leaves them for algae to use. Likewise, if there are too many nutrients present for the amount of CO2 in the water, the plants will not be able to use it all up and some will be left for the algae. Light comes into play in that the more light there is, the faster many plants will photosynthesise. Because of this, there will be a greater demand for CO2 and nutrients. So as there is an increase in light, there must also be a proportionate increase in CO2 and nutrients. Just as each one of these elements can be too high, they can also be too low. If the lighting is too low then there will be an excess of CO2 and nutrients, and there will be dying plants. If nutrients are too low, then the hobbyist will have a situation where there is nothing for the plants or for the algae. In a case such as this the hobbyist will get a nice thick green mat of cyanobacteria, also known as Blue Green Algae."
Hope this helps?