Help! Algae Problem

[MadReefer]

Okay. Since I put up the T5 lights I am having a problem with algae in the tank, mainly on the front glass. It's yellow/brown and seems stringy as it moves with the pump blowing on it. I have set the lights a s follows:
Actinic on at 10:00am with daylights at 11:00am
Actinic off at 9:00pm with daylights off at 10:00pm
I just changed the lighting schedule to turn on 2 hours later four each light which would make it actinic at 12:00pm and daylights at 1:00pm. I figured no one can see them anyway; I get home after 5:00. Is there anything else I should do? I do a 8-10 gallon water change every 2 weeks. Someone suggested dosing with magnesium, good idea?

Thanks,
Mark

 

[jazzsam]

I was doing really good with my T5 until I put a large mirror behind the tank. Then I got hit really hard with algae.

 

[MadReefer]

Sam,
Goodpoint. My tank has a mirror back; its mostly covered with algae already though.

Mark

 

[jazzsam]

My theory on it was that the mirror added way TOO MUCH light. It actually started buring my corals.

 

[MadReefer]

I don't have that problem. Like I said there isn't much in the way of a mirror anymore, plenty of green algae on it. Do you think I should try the magnesium?

 

[jazzsam]

I don't know much about that. All I know is that excesive light did it for me. Did you move the tank closer to natural light also?

 

[DaveK]

Most likely by changing to T5 lighting you increased the amount of light in the tank, and this caused an algae bloom because you have too much in the way of nutrients for the algae. This in mostly in the form of nitrates and phosphates.

To control algae you need to control nitrate and phosphate. Just because your test kits for these read low, do not think that you don't have a problem. A lot can be bound up in the algae itself, the live rock, and sand bed, if you have one.

I would recommend you remove as much algae as you can. Then vacuum the sand bed and blow out the live rock with a power head or turkey baster. Also, clean any mechanical filter media. Be sure to clean this media at least every week.

Next evaluate your filtration system. Is it powerful enough for your system? Is your skimmer large enough? You need this working correctly so you'll remove waste products that are major sources of nitrates and phosphates.

Also, evaluate your feeding schedule. You may be over doing this.

Look for other sources. This could be low quality carbon, or your tap water if you are not using RO/DI water, or frozen fish foods.

You can help the problem somewhat by reducing the photo period. I'd reduce it to 8 to 9 hours a day, until you get the basic problem solved. Then you can increase it.

I fail to see why the addition of magnesium would be a big factor in algae control. However, a low amount of magnesium can cause problems in other areas, mostly in the area of maintaining the calcium, alkalinity, and pH balance of the tank.

If you are planning to use magnesium as a supplement, first get yourself a test kit for it. Then measure the existing amount and add the supplement to bring it up to level. If magnesium is low, you may need quite a bit to bring this value up. Also, if it's low you may want to consider using a different brand of salt, one that doesn't mix low for magnesium.