Nice resin coverage on your WW Persephone. I agree with what your saying on the algae too. Had it before when i used rockwool and doesnt affect the smoke or the health of the plants.
yeah hasn't seamed to affect it at all.
The frost is just something out of this world. Looks like you found your pheno within the whitewidow genepool.
As you mentioned the algae is due to the light.. it's green which means that it has active concentrations of chlorophyl , as you mentioned if you can get something to block light penetration it will stop it from becoming invasive. As long as it stays away from your res and your res is covered you should be ok. Looks like you don't have a res though, but in any case your water source.. maybe a silver lid lining over the pots etc will do the trick. You obviously know what your doing