Actinic Lighting and Hair Algae

[GMGQ]

I think any light will promote algae growth over time if you have nitrate issues as well. Obviously MH more than Actinics. But if you have actinics on for almost 12hrs/day, I would definitely consider it a factor in HA.

You should get a timer and limit how long you have them on for. No worries.

[TheReefGeek]

Sure any light can grow algae, but you also need the nutrients in your system to feed that growth.

LOTS of setups run actinics 12 hours a day with no hair algae growth problems.

Heck im not running actinics and I have hair algae, and when I did run actinics I had zero hair algae, so what does that tell ya? That nutrients are the problem, not the actinics.

And the actinics don't contribute much light compred to main lights usually, so cutting back on main lighting from say 10 down to 8 hours would probably have a much bigger impact that limiting actinics.

Although actinics main function is usually visual appeal, they also greatly impact coralline algae growth IME, when running actinics my coralline was probably 5 times more prolific than it is now, so they do have use other than visual appeal.

I would put your actinics on a timer though, for ease of use.

[GMGQ]

That doesnt tell me actinics are not the problem. You're still running another source of light. The equation is:

Nutrients + Light = Algae

Whether it's actinics or another source, any light still plays a role in the growth of algae. Now if you had NO LIGHTS yet still had hair algae, then you can say 'lights' are not the problem. It's like when people cook their LR. No light = No algae.

With any source of algae, yes, you want to tackle the root source of the problem -- which are Nutrients.

But in the short term, if he cuts back on the lighting period, the hair algae should slow down as well.

Originally Posted by TheReefGeek

Heck im not running actinics and I have hair algae, and when I did run actinics I had zero hair algae, so what does that tell ya? That nutrients are the problem, not the actinics.

[TheReefGeek]

I wouldn't want the hair algae to slow down because of a reduction in light, because then I wouldn't know if I am taking care of the nutrient problem or not.

In your above equation, you will always have light, so if you want no algae, you have to reduce nutrients.

[GMGQ]

His question was:

Originally Posted by Jaws

I'm concerned that my actinics ... might be contributing to hair algae growth.

Short answer: Yes.

In my example of cooking LR, there is no light therefore no algae. That's why HA infested LR turn bone white. Obviously you cant do that for your display tank. But theoretically you can have nutrients and no algae.

Originally Posted by TheReefGeek

I wouldn't want the hair algae to slow down because of a reduction in light, because then I wouldn't know if I am taking care of the nutrient problem or not.

In your above equation, you will always have light, so if you want no algae, you have to reduce nutrients.

[TheReefGeek]

His question was actually:

Can too much actinic lighting be attributed to hair algae growth.

And my answer is no, not any more than lighting in general.
Nutrients are the problem, not the actinics. If you want to solve hair algae with lighting reduction, you will have to kill all your corals to do it.

[Samw]

Curious, does photosynthesis equate to growth in algae? If so, would you expect oxygen to be produced by algae when the lights are on? Because in my tank which contains all sorts of algaes, turning on only Actinics light in a dark unsaturated low oxygen tank produced 0% additional oxygen (when measured by my dissolved oxygen meter). To me, that means photosynthesis is not occuring anywhere in my tank when only the Actinics are on and thus the Actinics can't cause algae to grow significantly (at least not with 96W of it).

[GMGQ]

Well you're getting into semantics now. Obviously you dont want to reduce your lighting to say 1hr/day. But light does "attribute" to HA, in a system that has nutrients.

I stick by my equation of: Nutrients + Light = Algae.

Reduce either Nutrients or Light and the Algae will not grow as profusely.

But I totally agree that the ultimate goal is Nutrients = 0. No question. (BTW, feel free to include Phosphates as part of the problem as well).
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It just sounds like Jaws is a busy guy, sometimes leaving his actinics on from 9am-12am over his nutrient filled tank. In the short term, he definitely doesnt need to leave the actinics on for 15hrs/day. So by getting a timer to automate and reduce the lighting period, he should see some immediate results. The reduction of nitrates is usually a long term process.

Originally Posted by TheReefGeek

His question was actually:

And my answer is no, not any more than lighting in general.
Nutrients are the problem, not the actinics. If you want to solve hair algae with lighting reduction, you will have to kill all your corals to do it.