How much light is needed for SPS growth?

[Jan]

What is the rule for determining enough light for SPS growth? How many watts per gallon are needed/recommended?

[Boret]

What is the rule for determining enough light for SPS growth? How many watts per gallon are needed/recommended?

 

I really don't think you can apply a rule of thumb for it. You have so many different dimensions for the same gallons that it would be almost impossible to come up with a formula. The only thing that would make sense is to consider the penetration of the light for a given depth.

[Jan]

I found some guidelines. Thank you. It's approximately 4-8 watts per gallon for a reef. Of course depth, clarity, etc.. are all contributing factors.

http://www.liveaquaria.com/PIC/article.cfm?aid=30

http://kb.marinedepot.com/article.aspx?id=10204

 

I really don't think you can apply a rule of thumb for it. You have so many different dimensions for the same gallons that it would be almost impossible to come up with a formula. The only thing that would make sense is to consider the penetration of the light for a given depth.

[zygote2k]

I think water quality has more to do with sps growth than anything else. Why don't you borrow the PAR meter and measure your light levels in your tank and go from there.

[Origami]

I found some guidelines. Thank you. It's approximately 4-8 watts per gallon for a reef. Of course depth, clarity, etc.. are all contributing factors.

http://www.liveaquaria.com/PIC/article.cfm?aid=30

http://kb.marinedepot.com/article.aspx?id=10204

 

Jan, I think a more appropriate measure is not the old "watts per gallon" figure but PAR (photosynthetically active radiation - What Is PAR?) since it more directly measures the light that can be used by our corals while the former is so general and does not take into account either bulb efficiency or spectrum.

 

Three Websites You Should Know for Reef Aquarium Lighting

 

This is a good article from Sanjay Joshi's site: http://www.personal.psu.edu/sbj4/aquarium/...tosynthesis.htm

 

As you may note from Sanjay's article, it's hard for us to come close to the PAR found on a real reef. We can measure it, though. WAMAS has PAR meters available to borrow. Your closest keeper of the equipment is JMsAquarium.

 

Justin (ctenophore) recently had some thoughts on PAR values on this thread: http://www.wamas.org/forums/index.php?s=&a...st&p=276477. He was citing good coloration in his new greenhouse (naturally lit) with PAR in the 450-550 range at the bottom of some of his tanks.

[Boret]

I agree with both zygote2k and Origami2547. You are going all wrong about it with a rule of x gallons per watt.

A very tall and narrow tank, let's say over 35" tall will do poorly with a light bellow 400W. You will probably need a reflector that concentrates the light. That tank could easily be 50-60 gallons. The 4 to 8 watt per gallon is a large variation. So in a 100 gallons you are ok with either 400W or 800W!!! Well, that is quite a difference. It is easier to consider the specific dimensions of your tank and go from there.

You have a 75 gallon tank that is 21" tall, right?

About 1 to 2" of sand and probably about an inch from the rim to the top of the water. So you have about 18" of water. Now consider the placement of your rock and how far up is the closest to the top (I think I remember it being just a few inches). Consider also if you have different tiers, ledges, etc...

 

Keeping that in mind you can see how you could place SPS in the top and have enough PAR with 150 or 175 watts. But maybe you want to remove some of the rock and have the corals about 10-15 inches below the surface then you might need 250 instead of 150.

 

I have a 92 gallon tank and 1 single 400watt is enough. It is a corner tank and I really can't put two reflectors in there, but if I had a 90 gallon 4 feet long tank a single 400 wouldn't work, I would need at least 2 250watts. So even though the 90 has 2 gallon less of water capacity I still would increase the total watts to 500w because of the dimensions.

[Sikryd]

A lot of people on here are pretty experienced with growing sps.

 

So I would say it would be a little easier to post your setup, or what you would like to do, and people could let you know from their experience what your scenario would be like.

 

300 par at the surface of the water is sufficient to grow sps in the top of your tank. Sans the par meter, you can try a piece out and see how it does. I'm sure someone could give you a frag of something to see how it works out for you.

 

I have grown SPS with T-5's at the bottom of a 72g bowfront.

 

There are a lot of factors that can affect light penetration. Water quality and clarity being #1.

 

Sps isn't as hard to grow or maintain like it was a few years back with all the new equiptment and lighting.

[reefmontalvo]

I noticed great SPS growth with my dual 250w 14k MH's but I also noticed conistancy is the key in most cases. I also use a carbon reactor to help get clarity in the water column.

[ctenophore]

How much light is needed for SPS growth? A basic guideline I would say is a minimum of 125 micromol/m^2/s^-1, anything less than that most sps will fade and not grow. Many species require much more, but the "easy" corals (monti digi, cap, etc) should do okay with that. Borrow the PAR meter and see what your light fixture provides.

 

Edit: the WAMAS apogee PAR meter provides the number in the units I mentioned above.

Edited August 23, 2009 by ctenophore