Hi,
Well, In absolute terms reflectors alone won´t necessarily induce algae. It´s best to think in terms of the light intensity versus the amount of CO2/nutrients being dosed for that light level. High light levels cause a high demand for nutrients/CO2. It´s very difficult to say in any one tank what light level will result in which demand because there are so many variables. That´s why the Watts per Gallon WPG rule of thumb was developed. At WPG between say 1 and 1.5 you could typically get away without injecting CO2 and the nutrient demand is relatively low. Unfortunately, the WPG rule was developed before T5 lights were invented. It´s estimated that T5 plus reflectors increase the intensity of light by as much as a factor of 2 to 3 when compared to T8 or T12 lights used in the original WPG calculation.
This means that many cross the threshold of CO2 injection requirement without realizing it. If you are at or near the CO2 injection threshold therefore, yes, removal of the reflectors could conceivably bring you below the threshold.
Underdosing almost always results in poor plant health and subsequently, algae. Again, it´s difficult to quantify underdosing because dosing must always be in relation to the light level. Flow, number of plants, substrate type and other factors also contribute and complicate the issue. Severe underdosing causes an immediate impact whereas slight underdosing may not be that noticeable.
Hope this helps.
Cheers,