Algae bloom under Metal Halides - HELP

[troyrb]

My 30g reef tank is 10 months old and the levels are:
Ph: 8.4
Ammonia: 0
Nitrate: 1mg/1
Nitrite: 0
Alk: 10 dkH
Phosphate: 0
Calcium 400
Temp.: 81
Gravity: 1.024

The tank was going great with tons of coralline grow and no algae grow. A month ago I change my tank from 110 PC bulbs to a 10k 175watt metal halide. Shortly after making the change I started getting a bloom on all types of algae, mainly hair algae. It is now starting to cover the corals. I harvest it once a week and do weekly water changes but it grows right back. Even the coralline is starting to decline. I have 30 turbo snail and a couple hermits but they don't eat the larger hair algae. I also use a 5 stage RO/DI unit to filter the water. I only have three small fish in the tank and feed then frozen brine shrimp once a day. I only feed them a small amount each day.

I have no idea what is causing the algae bloom and I'm getting very disgusted that my beautiful tank is now full of algae. All of this started when I got my 10k metal halide, so I was thinking of trying a 12k bulb. Would this help anything? Can anyone recommend anything to try or has anyone had a similar experience? Thank you.

 

[delphinus]

I had to go through an algae bloom when I switched from fluorescents to MH. It lasted about a month or maybe even a little longer (certainly not longer than 6 weeks). Not sure what to suggest -- maybe some extra hermits (although I agree, it seems that when the algae is like this nothing will eat it). But that's what was suggested to me -- load up on the herbivores. It seemed to help.

What kind of bulb is it?

Going with a higher K bulb "might" help a little bit but you need to be careful with those bulbs as they age, the spectrum can shift right into a range where they grow algae speactularly. I had 2 14K bulbs that got terrible as they got to about 10-11 months old. I couldn't figure out why I was goriwng such terrible algae but then I replaced the bulbs with 2 10Ks and I kid you not, the stuff was gone within a week. So there is truth that bulbs need to be replaced every 10-12 months!