Help me undestand light better

[symon_say]

I will be setting a tank in a few months when i move to my new home, i'm new to saltwater and have been reading books and forum to try to get as much knowledge as i can get, i'll set a FOWLR but might eventually get some corals, maybe the lowest maintenance i don't know, but i need to clarify something like i did when i was planting my freshwater tank. I have read that you need about 4-5x watts per gallon, but isn't more important depth of the tank than the gallons it have??

For example, a 75g tank is L48xD18xH20 but what if i custom made a tank that is L48xD24xH20 they have the same depth and light should penetrate the same cause volume of water won't matter in this case, or water volume will affect how the lights goes intothe water and to the corals??

 

[Waddi]

Your right about the depth, but remember that if you make it wider in the middle, you may have some dark spots, and the more wattage the better.
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[Northstar24]

A 24" deep tank will require more light than an 18" tank, as the deeper the tank goes, the harder it is for the light to penetrate all the way to the sandbed. If you're doing a 24" deep tank, you'd probably want a 6 bulb T-5 fixture, metal halides, or LED's of some sort. This is assuming you want to be able to eventually keep anything offered in the trade. If you think you'll do corals, its probably smarter to buy the right lights the first time, versus not having enough light to keep what you want

 

[symon_say]

I want to made the 20" deep, and 48x24 in the base, strong light should be over LR cause there is were corals will be, right??

If so i can get smaller lights to give some lights in darker spots, right??

Problem is that is really hard to find things for saltwater aquarium (ironic, YES), but most of the equipment i'll have to DIY or buy it in USA and import it. So cost is a big thing for me in this case, but for now i'm just learning and saving.

 

[ErinCahir]

I have just under 5 watts/gallon (which, by the way, the watts/gallon thing is just a guideline, it's not set in stone).
My tank is 30" deep... and I have no problem keeping lower light corals (mushrooms, zoas) in the lower areas of my tank.
I don't know a lot about lights, but I know MH penetrates deeper than t5's do.

 

[little_fish]

If you have a deeper tank you are going to want a metal halide setup, because the lights penetrate much deeper.

But a 20'' tank would do fine with a t5 setup, i would aim for one that has at least 6 bulbs.

But if you have the DIY it, i think it would be easier to put together a metal halide system anyways.

 

[time2reef]

If you are truly looking to figure out what is best you will need to consider LED.

The new technology is some of the best out there.

This is some info good info and comparison with LED on one side and MH on the other.

orphek

 

[symon_say]

Thanks, i have been reading about everything, and from what i see, there is not a definitive answer for this question, what i have read everywere is about watts/gallon, but i think that ain't accurate cause deep of the tank is more important that gallons.

Is there another way to determine what kind of light somebody needs for X-deep, i ask this cause a 55G, 75G, and 100G have about the same deep difference is just a bigger base, a let say you want to have the some location for for your LR in those tanks, light over then should be the same, true that there will be dark spot cause of the bigger base, but this can be covered from some low watt leds.

I ask this cause i don't see the point of having all your tank under high power lights just to grow some coral over your LR and around then, i think that's a waste of money.

Don't know if you can see my point, just trying to understand evertything a little better than the "average joe".

 

[little_fish]

You are right, the watts/gallon isnt very accurate but it works for t5 and metal halide lighting pretty well. If you have a deeper tank, like 25+ inches, i would use metal halides because they penetrate the water better.

The reason you need more lights for the larger tanks is because there is also spread, so if you have bigger base you need more lights for spread of the tank. Hence why a 75 needs more light than a 55 even though they have the same depth.

And if you dont want to grow corals, then there is no need to buy nice lights.

 

[symon_say]

In my case, i'll start with a FOWLR, but i know i'll corals in my tank, so i want to buy lights from the beginning cause i don't want to spend twice, when i get it, i'm gonna get 4 T5HO fixture, and when i start adding corals i'll get another to have a nice set.

But my questions come from not understanding why you need high power lights for all your tank when you have coral i just a few spots, why not put the high power lights right above the corals and some low power light for the rest of the tank??

 

[little_fish]

You could do that, but you are going to find you want corals everywhere. Plus, corals grow, you need to leave them space to do that. And it would be very difficult to keep all those different fixtures up there there.

Personally, i would recommend you get this light (90 gal or less, bigger go with MH):
Aquarium Lighting for Reef Systems: Current Nova Extreme Pro Saltwater T-5 Fixtures

With this light you will be able to keep anything you want, where every you want.

 

[Northstar24]

You'll eventually want corals pretty much everywhere in the tank to make it look right. Hannah is right on. If you're going to spend the money to buy lights to keep coral, you might as well spend it wisely and get lights that will cover your entire tank

 

[time2reef]

I totally understand being the average Joe myself. What you have to start with is an idea of what kind of tank you want. If you want reef then you are pretty much resigned to PC, MH, T5 and LED or a combination of these.....

The holy grail currently is MH supplemented with T5.

I don't pay any attention to watts per gallon. I look more are what I am keeping and what I would like to have in the future. Two things to look at are PAR and PUR. PAR is the intensity or brightness. The deeper the tank the more the PAR decreases.... PUR is the actual useable radiation a bulb puts out. This is useable radiation by coral standards.

You can have a ton of PAR and still not have a good lighting system for your tank.

I don't run MH. I am completely over to LED and very happy.

Thanks, i have been reading about everything, and from what i see, there is not a definitive answer for this question, what i have read everywere is about watts/gallon, but i think that ain't accurate cause deep of the tank is more important that gallons.

Is there another way to determine what kind of light somebody needs for X-deep, i ask this cause a 55G, 75G, and 100G have about the same deep difference is just a bigger base, a let say you want to have the some location for for your LR in those tanks, light over then should be the same, true that there will be dark spot cause of the bigger base, but this can be covered from some low watt leds.

I ask this cause i don't see the point of having all your tank under high power lights just to grow some coral over your LR and around then, i think that's a waste of money.

Don't know if you can see my point, just trying to understand evertything a little better than the "average joe".

 

[time2reef]

These posts are correct. The other thing to consider is cheaper lighting will put the wrong spectrum in your tank and you could fight algae issue due to that. You could do spotlighting for corals but that can get expensive with the PAR38 bulbs.......
The tank would also look odd with different lighting in different areas.....

It sounds like you are thinking correctly in buy what you will need later on to save you the expense of buying twice. Do your research and pick something that others have had good success with. I ventured out on my own with a fixture that no one had success with thinking I could make it work.....I've now thrown that idea out in the trash.... hahahaha

You could do that, but you are going to find you want corals everywhere. Plus, corals grow, you need to leave them space to do that. And it would be very difficult to keep all those different fixtures up there there.

Personally, i would recommend you get this light (90 gal or less, bigger go with MH):
Aquarium Lighting for Reef Systems: Current Nova Extreme Pro Saltwater T-5 Fixtures

With this light you will be able to keep anything you want, where every you want.

You'll eventually want corals pretty much everywhere in the tank to make it look right. Hannah is right on. If you're going to spend the money to buy lights to keep coral, you might as well spend it wisely and get lights that will cover your entire tank

 

[symon_say]

Thanks, i know there is a lot of info in this subject, but giving that you're helping me, i'll keep trying to understand better , i'm planing everything upfront, not like i did with my FW tank, that i spend a lot of money on things i don't use now, cause i didn't get the proper one upfront.

Right now basically there are 3 types of light for reef tanks, T5HO, MH and LED, my original plan was to use T5, i want to have a 100G tank, and i was gonna get a fixture for 4 T5 bulbs, and another one for 4 more, and i'll have 8 T5 in my tank with i think is enought in 2-21" deep tank to have most of the corals.

Those light will use about 428W, if i go with MH i'll have to get at least 2 150W MH + 4 T5 lights, that will give me 516W, those fixtures are somehow equivalent from one kind and the other, but if i go with LED's do i need the same amount of W, or do i use less W from a LED fixture??

I ask cause i have some experience with LED's and i might be able to DIY a LED fixture, and cut some cost from the fixture itself and from my electricity bill (is important to me cut costs cause i'm getting married this year).

PS: i'll read later about LED fixtures and some DIY.

 

[time2reef]

The wattage is not as important with LED. Most people are using 2 or 3 watt LEDs. The problem is that most of the LEDs on the market in white are only 6500- 10k. This is a huge issue for us as it would make the tank look too yellow and not provide the right spectrum for our corals. A lot of the manufacturers offset the white look with a lot of blue. This increases the PAR as well because the blue light penetrates the water and doesn't lose PAR as quickly as the white.

Look for LEDs around 15k and see what you find.....

Remember, there is a difference between fixtures that give the "look" of 15k and fixtures with 15k LEDs.....

 

[symon_say]

Thanks, for now, i'll be keeping my original plan of 4 T5 and later 4 more, until i think i now enough about LED's to give it a try.

 

[time2reef]

No problem. Good luck I am sure that you will enjoy the tank and have great success!!!!