I'm having a hairalgea problem in my 29 gal reef tank. It's been set up for about 4 months now and has had no problems nothing has died exept for a peppermint shrimp died about a month ago. Just recently I've been getting a whole lot of hair algea. Here's all my tank stats, hopfull some one can tell me what to do.
29gal tank
filtration- cascade 1200 and a power head
40lbs live rock
40lbs live sand#ed_op
temp 78
Amonia, nitite and nitrate all 0
slainity 1.022
suplemented with sea lad 28 blocks as needed and kent marine liquid calcium, stonium, and tech 1 (not as often as I should)

inhabitants
yasha gobie
lawn mower blenie
6 line wrase
cleaner shrimp
peppermint shrimp
randli pistol shrimp
about 15 hermit crabs
5 turbo snails
about 6 nasarius snails
yellow sea cucumber
britle star
and a small asortment of polyps and soft corals
some people at the LFS recomended chemi clean and a poly filter. I did the chemi clean two days ago and the poly filter yesterday. Its made my water very clear, but hasn't seemed to affect the algea. They also recomended a small tang or pygmy angel to eat the algea, would anyone else recomend this?

This is my first reef tank so any recomendations would be helpfull.