Cloudy/green water! Help!

This is my first saltwater aquarium and I don't know what to do!
I started it up 4 months ago and there have been no problems. I let it cycle for a month before adding animals.
It's a biocube 29 with 40 lbs live sand, 15 lbs live rock, some hermits, snails, two zoe frags (one isn't doing too hot), an emerald crab, a small anenome, and a star coral frag (which also is not surviving). A month ago I added a single firefish goby. He's doing fine.
I made a mistake shortly after adding the frags in that I left the light on for three days. Basically fried the coral. The anenome and zoe survived. Needless to say I bought a timer after that!
The tank has good circulation. I added a small power head. I left in the bio balls and added a small protein skimmer in the back which seems to be doing its job.
Two weeks ago, the water started getting cloudy. I tested ammonia and it was 0, nitrite was 0, nitrate was 0. pH 8.3. I did a 20% water change and it was clearer for a while and after a few days was very cloudy again. And green. I changed the water again 5 days ago and same results. When I changed the water both times I siphoned snail poop, etc. off the bottom. I got most of the crud out. My tank is now cloudier and greener than ever (i can't see most of the rock now!) Help!
Karlee

A uv filter will help alot to rid the green water. You are getting a algea bloom. The 3 days with light probably triggered the bloom. What are you running for lights and how long are you leaving them on for? Too long of a photo period will make the problem not go away. once we know your lighting and photo period we can see if that is right and the uv will kill the algea. After the problem is gone you shouldn't have to run the uv all the time. I have one just for problems like this. If I was closer I would let you borrow it.

Bio balls should be removed ! They trap excess nutrients ! As far as your water i have seen this happen before with a friends new tank ! He added product to speed up cycle of new tanks can't remember name of top of my head but it cleared it up ! When nothing else would !!! I will ask him what he used !

I've used purigen to get rid of green algae blooms in the past. Took care of it in just a couple days.

I'd also decrease your photoperiod for awhile.

Run some fresh carbon and leave the light off a couple days

Thanks! Those were really fast responses.

As for the lighting, I have the original 10,000 watt fluorescent and an actinic blue light during the day (12 hrs.) and just a blue LED at night.

I will try all of the above- I'll remove the bio-balls (I've heard the same thing from other people) and shorten the light cycle to 6 hours instead of 12 (I want to give my inverts a little light) for a week, and if it clears up after that I think 8 hours would be better. How does that sound? I'll put in a fresh carbon cartridge. I'll look up purigen and see about getting a UV sterilizer (I had been thinking about getting one anyways).

I'll keep you all updated on how it works out!

Just cut light down until algae goes away ! Then prObably put it back to your normal schedule after it clears up i run my t-5 's for 12 hours and halides for 7 On a normal bassis ! Purigen can be bought at most Lfs it I's just an absorption media like carbon but better absorbs way faster !!

Kent pro clear was what my friend used it cleared it up fairly quickly if i remember right !

Dittos to the above. agree with leaving light off or shorten the photo period to only an hour in the evening so you can feed. We had an excellent lecture from Randy Reed from Aquaculture (see facebook) on algae. It is fascinating and a good learning process. Took me about a year of hard study to begin to understand. Mostly don't worry, it is all natural and will be controlled in natural ways. I put some halimaeda in my 29 and it adds greenery (I was a freshwater guy and I missed the green) and it competes with the algae for nutrients. Of course it competes for calcium too, but the lighting in my 29 is inadequate for SPS anyway, so I only have soft corals (LPS) like you do in that tank.
Call if you want a sprig, I can deliver a hunk, it roots in your sand and is not invasive. 218-721-4692. Nick