bubble algae/valonia algae

hello all, i'm loseing the fight against this stuff.every weekend i'm
siphoning this crap out of my 180, and about 4-5 days the stuff is makin
a comeback. i remove it from the substrate & LR then the tank looks good
4 a while but it's right back in no time. i feed every other day,only 4
small reefsafe fish,additives-- once a month-iodine,stront/moly,drip
kalk nightly, trace elements, thats it. my pc lights are on for 8 1/2
hrs. is there any thing that i could increase/decrease to curb this and
hopefully get rid of it. thanks