Marine Lighting?

[lljdma06]

Hello,

I'm usually at FW, but I've just read a very large thread in the nano section, you know who's, and I was curious at to how you guys over at Marine light your tanks? I'm impressed by the myriad of organisms you can cram into such a tiny little space.

I keep planted FW, and I have Corallife T5 fixtures in my small tanks. One 10g tank has 2.8WPG and the other 15g has 3.7WPG. These fixtures are about $35-$40 US dollars for a 28W fixture and a larger fixture in a 36g tank in Miami is a 2x65W T5 fixture and was about $130. They give very good light for my needs, but I'm curious as to how you determine what is adequate light for growing corals? I have heard about Metal hallides, they are used in planted tanks, but seem to be lessening in popularity since the introduction of the power compacts and other such fixtures, at least in my realm. Is there a formula that you use? I am curious because I'm taking the fixtures home with me and I am trying to see if they can be used somewhere else. The bulbs in them are able to be replaced.

I'm just curious, yes the marine bug may be hitting me...especially when I move back to Miami, FL. Marine central.

Thank you very much, and if this question has been answered a hundred million times already, please feel free to direct me to a thread where this question has been answered.

 

[fraservet]

Lighting in marine tanks varies greatly depending on what is in the tank.

A fish only tank +/- live rock requires very little in the way of lighting. Even just a couple of t8's - one actinic and one white - will be sufficient for displaying the fish well and coralline algae growth.

Once you start looking at reef tanks, things become more complicated, as there is a wide range of requirements for different corals. Some will survive with just the basic lighting above and will not cope with intense lighting, while others need very strong lights. This is a mistake lots of beginners make, as they buy the corals they like the look of with no regard to the different needs.

The depth of the tank, and the level that different corals are placed is also very important. IIRC t5's penetrate about 18 inches before the quality of light deteriorates greatly, while metal halides give better penetration.

Metal halides are very good for large/deep tanks and up until recently were pretty much essential to keep all but the easiest corals.
As you said, the advent of power compact lighting has changed things a bit, as it is now possible to get a large wattage in a small area. They are especially useful in nano tanks as they are easy to fit into hoods, and cause a lot less heat than halides, so it is easier to regulate water temperature.

In conclusion - in my opinion, if you have a tank that is 4ft or longer, and/or is 2ft or more deep, you are probably best getting halides for a reef tank.
For very small tanks, power compact is probably best in most situations.
For sizes in between (2-4ft), it really depends on what you are trying to keep.

Hope this is useful. I'm sure others can give you more specifics on lighting for different corals etc if necessary.

 

[maestro]

I dont really like the watts per gallon rule, its much better imo to actually look at the amount of light that you have, for example 4 watts per gallon a a little 20 gallon tank wont grow corals that 200 watts of light would on a 100 gallon tank.

Generally speaking for hard corals that requre alot of light you need either halides or atleast 4 t5 tubes.

T5 compacts are that great because they are inefficient, alot of light from the tubes rebounds back into the tubes instead of being reflected downwards.

As an example on a 4 foot tank you would want atleast 2 x150 watt halides or 4-6 T5 tubes to grow hard corals, sodt corals require atlot less, even a couple of t5's would probably do.

 

[Navarre]

The difference in lighting is subtle to the eye but important for the welfare of the tank when comparing freshwater and marines.
Freshwater lights are setup to give greater spectrum to the plants as well as show off the fish. The lighting tends to be in the red spectrum so lights like Grolux tend ot be good for freshwater tanks.

Marines however have very few plants.. almost none in fact other than algae and most of that is unwanted! Many people that try and use the same freshwatre tubes in their reef tanks find algae growth to be at high rates. The colour temperature for marines tends to be from 10k to 20k which is moving from white light ot blue light. This helps limit algae growth and still provides corals wth enough energy to break down the food they catch.

The fixtures in your freshwater tanks should be fine for using marine tubes in but if you are thinking of changing an exsisting freshwater setup over to marines then you will most certainly need to change the colour spectrum of the lights you currently have.

 

[lljdma06]

I apologize, I think I phrased my original question incorrectly. I understand that there is a difference in the color temperature used for marines as apposed to FW. I use 6700, whereas a marine tank, at least the bulbs I have seen will use 10k or even the blue acitinic (sp). I would never use my FW bulbs in a marine system, the color temperature requirements are different.

I guess what I'm asking is how do you determine how much light is enough to grow corals? As a freshwater plant grower, I use WPG and plants are ranked based on their light levels. For example anubias are considered a low-light plant, which means they'll do well in tanks with a WPG of less than 1 or 1.5. The higher the WPG, the more light demanding plants you can get. That's overly simplistic, you need CO2 and ferts as well, but this is the basic rule. Is there a similar chart for growing marine corals? Or do you guys just wing it? How do you know how much light is enough? For example, I know exactly what plants I can put in my tank because I know how many watts I have in each tank. That's where I'm going. I understand that WPG doesn't apply well to every situation, it doesn't work for larger tanks nor does it work for the very small tanks either. It also doesn't work for tanks deeper than 21".

Perhaps my questiona are too odd or worded wrong, and for that I apologize. They are strange questions, I know, and I'm not even planning to go marine anytime soon, if ever. I'm just very curious about the other side...

 

[crazyelece]

There is a basic rule of thumb of 5 watts per gallon to be able to keep the most corals. Every coral is different just like plants. However saltwater aquascaping allows the aquarist to place corals at different levels along a rock wall. Also you can build overhangs that can shade light in a highly lit tank for those corals that like little to no light. You can do amazing things with the aquascaping in a saltwater setup where in fresh water you are mainly limited to the substrate to root the plant into. Also as said above the wattage is also dependant upon the height of the tank as halides can penetrate further than flourescents. So the deeper the tank the higher wattage you would need even for the same volume. For example a 20 gal long tank vs. a 20 gal tall tank.

 

[Opcn]

65 watts over 25 gallons is considered moderate, High can reach way up, But 6700K bulbs are used, especially in keeping uber shallow water photosynthetics like maxima and crocea clams, and some anemonies

 

[lljdma06]

Thank you, that's what I wanted. Not that the other answers weren't great. They were, I learned a lot, but I'm the kind of creature that needs numbers or things don't make sense.

So essentially, I can have a 125W fixture over 25g and have the adaquate light to grow most corals. It's very simplistic, I know, there's a lot more involved, but that's the jist. Stick to more shallow tanks if your going with florescents, and arrange your corals according to their lighting needs. I'm just shooting off basic rules of thumb, I guess, from what I've read so far. I'm not even going to go into water chemistry yet, that's another thread.

By the way, planting plants is not quite so limited. In the Dutch style, many aquarists practice Terracing, and achieve multilayered affects that'll blow your mind.

Thanks a bunch, people at SW, if anyone else has a conflicting opinion, please feel free to voice. This is very educational for me.

 

[maestro]

Generally speaking if you want numbers then over say a 5 foot aquarium you would need 2 halides to cover that length and for high light corals you will need 250 watt halides.

Remember that because the marine bulbs have a higher colour rating they give out less PAR than sunlight tubes so you need more watts.

The problem aswell is keeping the tank temperature stable, if you use your example of 125 watts over a 25 gallon then you would find it really hard to keep the temp stable and your corals would suffer

 

[lljdma06]

I see. My 125 W fixture has a fan in the fixture. I don't know how affective that it, but it's a start.

 

[Navarre]

Fans are commonly used to help keep marine tanks cool (far cheaper than a chiller!) However this means that the evaporation for the tank is very much higher.
This is not a problem of course as long as you are prepared for more numerous top ups with RO water.

Another thing with corals to remember is that light is not the only important factor to consider. Many hard corals for example need extremly high lighting but they will perish if they are not in the correct flow. The true art that many never seem to appreciate is to have the correct lighting levels for all types of corls in your tank along with a varied amount of flow in your tank. Some coral prefer high flow and other like low flow.. so having a multitude of differnt levels of lighting and flow is vital if you want an invert tank to succeed.

 

[lljdma06]

I want to thank the people who contributed answers to this thread. I have a better understanding now of the differences between SW and FW lighting and it is appreciated. If you would like to close this thread for space reasons, I have no objections really, my questions have been answered.

Again, a warm thank you from a fellow hobbiest.