Ridding of Thread algae?

Did you have any before this and if not has it spread to other plants in your tank ?
The "has it spread" part is related to the tank having at least some of the conditions
needed to support it.
But usually light duration is the main factor in the answer to the "how to" on algae.
If the light is higher med level or anything up from there for the past several months now and you haven't had it before your tank is likely well balanced between the ferts you dose and what the plants use. In this case I suspect it didn't spread or not much
anyway. So just reducing the duration of time that the lights are on may be all that you need to remove it. But if you had lots of it start to spread fairly rapidly then it's gotten established and has nutrients as well as too long of a light period.
I always hve too much light for most any tank that I have simply because I like the algae and to a point, cultivae it. "Did you want that on the rock only or the rock and wall ?" is not a joke and it can be done...just look at my tank Exp #1 and you will see it only on the rock.
I only have 7.5 hrs in that tank/w the light so you don't need 11 hrs of light in a tank.
If the long hrs are for viewing in A.M. + P.M. then just time them to go out around noon till you get only 6 hrs till it goes away. Then go back to 7.5-8.5 hrs and it will stay gone. Just run them for a couple of hrs in the A.M. till you leave and back on in the P.M. when you get back for a total of 6-7 hrs but 6 is better.
But if it spread rapidly then you will also need to cut your ferts to be rid of it.
If using EI then drop the third dose of each of the M&M. If PPS then cut by 1/3.
By keeping the light down to 8-9 hrs after the algae is gone it should stay gone.