Algae can be affected by light, but it would be by a different mechanism then what SDW is experiencing. He is having salt build up that is blocking light and lowering par. This should never cause algae to grow.
Algae growth can be affected by the spectrum of the bulb. When bulbs get old, they tend to have degridation in the blue and pruple end of the spectrum, causing the color of the bulb to shift to the more yellow-red end of the spectrum which favors algae.
Regardless, algae cant grow without some sort of nutrients in the tank. First place to check is in the water column itself(test kits). Next youll want to look for detritus accumulation anywhere that can be slowly leaching po4 and no3 in to your tank, causing algae to grow. Finally, youll want to remove existing algae, and increase filtration. Living algae itself is a nutrient sink. If you simply remove its food source, then let existing algae die, it will return to the water column as po4 and ntirates, and cause algae to grow elsewhere in the tank. Its a long process, and my explination is pretty condensed, but I think it makes sense?