Lighting Problem- Metal Halide - brown algae YUCK!

[manialkie]

I hung a 175 watt pendant metal halide light 10 inches over my tank. I'm using a coralife 175 watt, 20,000 k bulb. To my suprise the light is slightly on the blue side. The tank became overrun with brown algae. Not even the turbo snails like it. I also did 2 large water changes to help get rid of medication right before hanging the light. WHAT IS THE PROBLEM? How do I fix it?

Additional Info:
I'm using tap water. The water is a little hard (250), pH is 8.0 ( a little high), nitrite is zero, nitrate is 20 ppm.

The algae is hard to describe. Its not filamentous or hairy and not in sheets. It is a thin, almost flat spotty layer that easily rubs off in extremely small pieces, almost like dust.

Before using the new lighting I used 2 Coralife 50/50 flourescent tube and got green and red algaes. Then 1 tube burned out and the brown algae took over. I cleaned the tank, scraped the algae, moved the tank downstairs, changed a lot of the water in the process, and switched to the Metal Halide pendant. The brown algae went nuts.

What next?

 

[kreach]

What kind of lighting were you using before? An upgrade in lighting can sometimes cause an algae bloom due to the better spectrum and higher intensity light.

Have you tested your water? What are your parameters?

 

[reefrunner69]

I also did 2 large water changes to help get rid of medication right before hanging the light. WHAT IS THE PROBLEM? How do I fix it?

What kind of water are you using? Tap? RO?

Aside from being brown, what did the algae look like?

Have you tested your water? What are your parameters?

Yep, need more info

What kind of lighting were you using before? An upgrade in lighting can sometimes cause an algae bloom due to the better spectrum and higher intensity light

Strongly agree here.

 

[manialkie]

I'm using tap water. The water is a little hard (250), pH is 8.0 ( a little high), nitrite is zero, nitrate is 20 ppm.

The algae is hard to describe. Its not filamentous or hairy and not in sheets. It is a thin, almost flat spotty layer that easily rubs off in extremely small pieces, almost like dust.

Before using the new lighting I used 2 Coralife 50/50 flourescent tube and got green and red algaes. Then 1 tube burned out and the brown algae took over. I cleaned the tank, scraped the algae, moved the tank downstairs, changed a lot of the water in the process, and switched to the Metal Halide pendant. The brown algae went nuts.

What next?

 

[Electrobes]

man.. you need to start using RO water. tap water has wayyy too many phosphates that causes cyano bacterial blooms.. I should know I started with tap water and REFUSE to go back because I got the same isaaues and a lot more than what you are experiencing now. The lighting helped the problem but really isn't the cause of all this. I would shorten the lighting some and start doing some water changes (not too massive) with RO water.

 

[two11devan]

You could try to use sheets of window screen to help your tank acclimate to the new lights. You can cut several strips to the size of your tank, layer them, and remove one every other day or so. This should help your tank adjust to the new lights.