Hi Fourmations,
I just went to check my suspicion it appears to be one of the beard/bear algaes
i stand by the boiling but will this completely remove the problem i think not as this has had a few days to thrive.
thus i would suggest adding a little co2 (a quick google for this part

)
now remember co2 will effect your Ph slightly!!!!!!!!
I wanted to add co2 for a short time thus i did a diy job so this may help short term but i thing all will agree your plants will love you for it
I got a two liter mineral bottle some air line an air stone and 1 air line connector i drilled the bottle lid placed the connector in the hole and applied some sealant this done i measured out a liter of water and added four tablespoons of sugar which i stirred in and dissolved as much as possible i placed the water in the bottle and added some yeast the bottle with yeast sugar mixture i left on the drainer over night with a balloon on it this was in case it froated over (i did not want to risk this going into my tank)
the next day the balloon had started to inflated this told me the co2 was present i screwed the lid on connected the air line to the lid and stone and place the stone near the filter in take the co2 created its own pressure and escaped in to the tank
do not use a glass bottle if the pipes get blocked it could explode sending flying glass
again i would point out the this
it will effect PH plants will love it.
remember to check daily as any pressure build up could be dangerous.
while this is a basic home brew treat the resulting liquid as toxic and dispose it when expired this is to get co2 and because nothing has been do to ensure safety or quality it could make you very sick
Mickey