George - look at where the thick patches of algae are in relation to your plants. It has grown where there are no plants to soak up the light, and nutrients from the substrate.
At the moment, it seems confined to those areas. However, as I think ceg said, algae is best compared to a predator. It is simply building up strength and mass at the moment. Very soon it will run out of space on the substrate and then attack your plants. Then you are screwed, especially since you don't have any clean up crew in there.
It will take months for your existing plants to reach enough mass to mount a fight back against the algae. At the moment, your tank is a ticking time bomb.
Well done for recovering it from its previous state. However, you need to seriously think about what happens next. If you do not do something, it is going to be all over very quickly.
You might be reluctant to buy new plants because of the cost. Think of it this way. How much is it going to cost to replace all of your existing plants when the tank inevitably crashes? Or, how are you going to feel sitting looking at a big expensive tank and hardware full of algae again?
For the sake of all of our sanity, please put some more plants in. You should also think about some shrimp and snails now as well, since you have successfully cycled your tank. My offer still stands to send you some clippings. It won't cost me anything - I have to trim almost as much plant mass out of my tank (which is smaller than yours) every two weeks as you have in total.