Puzzled About Lighting Levels

[mnew]

I have a 43 x 30 x 15 tank being made and am wanting to have live plants in it. I saw some tanks where the fish looked particuarly lovley and ask what lamps they were using. These were Hagen Power Glo which are 18000 K I can just fit a 40 W tube in widthwise.

My local fish shop suggested that a single 30 w tube would be adequate. However reading on this forum it seems that with my 300l 0r 80 gall tank I will only have 0.5 WpG even with my 40 w tube. It would seem that I should look at at least another two tubes or perhaps one extra tube and some reflectors?

Have I got this right? or is the WpG based on old incandesent bulb lighting? a 40W tube puts out much more that a 40W bulb. This tube I have says it is 160 Lux.

How many Lux per Gallon should we aim for ?

 

[Castellop123]

If you want OK lighting ( good for plants ) then I would suggest 3 - 4 WPG... That would mean you would need eight 40 watt tubes or four 40 watt tubes, all with reflecters ( as this usually doubles the tube's light intensity )... You can ofcourse, get more powerful tubes in the first place. T5 lighting, etc...

 

[BigIan]

Having the exstra lighting all depends on what else your putting into the tank...

if your injecting co2 and adding ferts in the substrate and the water column then you want 2.5+wpg of lighting. However if your just wanting some plants in there then having alot of light is just going to cause algae issues, so just stick with the 2,

To give you some idea i have 4 tubes on my 60 gal with presureised co2 ferts dosed daily and a highly fertile substrate

 

[Themuleous]

If you want OK lighting ( good for plants ) then I would suggest 3 - 4 WPG... That would mean you would need eight 40 watt tubes or four 40 watt tubes, all with reflecters ( as this usually doubles the tube's light intensity )... You can ofcourse, get more powerful tubes in the first place. T5 lighting, etc...

I dont really agree with that, 3 to 4 WPG over a 80g is a hell of a lot of light. You'd need Co2, lots of ferts, the whole hog. For a lower light tank I would aim for 1.5WPG (dont forget to use US gallons, not UK gallons for the WPG 'rule').

The WPG assumes that you have reflectors, so these are a must, they dont give you 100% efficiency they just help you get the light that goes out the top of the tubes into the aquarium.

With 1.5 WPG you could grow most things, there is a pinned plant list with a list of less demanding plants that would be ok for that much light.

Oh and dont worry to much about the k rating of light tubes, the spectrum they produce is far more important, avoid anything with to much blue as that'll promote algae, get ones with peaks in the red, blue and green spectrums.

Sam

 

[SuperColey1]

I am now confused, although I probs shouldn't be.

I have 2 x 18W with reflectors.

Do I have 36W or equiv to 72W. If it is 36 then the post earlier is very misleading.

In my tank I would have 1.5WPG with 36W and 3 with 72W.

Please confirm for us confused beginners to lighting and techy stuff. I always assumed that I had 36W before reflectors, and that now I have more efficient 36W with reflectors, therefore now being a true 1.5WPG and before a false 1.5WPG.

Can someone clear this up?

 

[fry_lover]

I was wondering about 3-4 wpg of light, some even suggest 4-5 wpg, that be some serious bright light

Your fish would need sun-glasses, surely!

to be serious i am wondering same thing myself, i got a 120 litre (26 gallons), fully planted with 2.3 wpg

Plants are Java Fern, Java Moss, Amazon Sword, Vallis, Onion Plant and Hygrophilia, is that enough light?

sorry to butt in your thread!

 

[Themuleous]

Reflectors are very misleading, the Arcadia ones even say on the box 'double the output of your tube' that is totally wrong and to be honest its probably false advertising.

Basically its like this, if you have an 18w bulb, it'll only ever produce 18w of light. you cant change. Now think about it, if you put this tube under a black coloured hood much of the light produced goes out the top of the bulb, and gets 'lost' into the black hood. So in effect only 50% of the light the bulb produces goes into the water. Now what a reflector does is to bounce this lost light into the tank, greatly increasing the amount getting into the tank. Now it'll never be 100% effective but would think it could get up to 80-90%.

Simple

Just for interest George had 2.2WPG over his 125lt rio and got glosso to carpet, why do you need more? If anyone fancies an interesting read, have a read of the amano light article in my sig, by the finch family

Hope that helps

Sam

EDIT - fry lover, its very difficult yo answer the question 'is that enough light' you have to match the lighting level to want you want to achieve in the tank. The plants you have are not demanding and so the light level you have is fine for them, but perhaps not so for more light demanding plants. However, adding more light is risky and if not matched by other factors, you;ll get major algae, so if the lighting you have is working fine with the plants you have, then leave it be

Match the light to the plants you want to keep not the other way around.

 

[cleekdaFish]

I have 2.3 , i can grow anything it seems like...but i have daylite and actinic and my daylite is 10k...

 

[SuperColey1]

Just for interest George had 2.2WPG over his 125lt rio and got glosso to carpet, why do you need more? If anyone fancies an interesting read, have a read of the amano light article in my sig, by the finch family

Sam

Just for interest, I turned off the sigs section because of all the ludicrously large pics and lists of peoples 'public' aquariums. which they must be with the 100 lines that appear at the end of their names, and you are now forcing me to spend 10 seconds of my valuable time turning them back on for 2 minutes. Thank you very much....................



.............p.s. Only joking with the attitude, but tis true I did have them turned off for this very reason.
Will look at the finch article

 

[mnew]

.............. avoid anything with to much blue as that'll promote algae, get ones with peaks in the red, blue and green spectrums.

Sam

err so I need peaks in the red blue and green spectrums but not too much blue? any recomendations of a tube make and type ?

 

[George Farmer]

The pinned lighting article should help.

 

[mnew]

I was wondering about 3-4 wpg of light, some even suggest 4-5 wpg, that be some serious bright light

Your fish would need sun-glasses, surely!

to be serious i am wondering same thing myself, i got a 120 litre (26 gallons), fully planted with 2.3 wpg

Plants are Java Fern, Java Moss, Amazon Sword, Vallis, Onion Plant and Hygrophilia, is that enough light?

sorry to butt in your thread!

No problem butting in.

I was reading in an Interpet book last night that was stating the same about light levels but it did say that to bear in mind the fluressent tubes give off approx four times the light per watt over normal incandessent bulbs.

I wonder if this formular is for incandessent bulbs, in which case if you divide the wattage needed by 4 you get a much more reasonable value for the number of tubes. Eight tubes accross a tank 15" deep is tricky to accieve, and the dispaly tanks I have seen never have this level of lighing

So I'm still puzzled

 

[mnew]

The pinned lighting article should help.

I had read that excellent article a couple of times before I posted. It would be a good idea to give a formular for Lux per gallon as that is a mesure of light whereas power is just a measure of the amount of electricity consumed, and so can not be used for comparing different types of light. (I'll take my elecrical engineers hat off now : ) )

 

[Themuleous]

Forget incandescent bulbs exist as far as aquariums go, they were replaced my fluorescent ones long ago so whenever we talk about bulbs we mean fluorescent And don't get to bogged down in the whole WPG or lux per gallon side of things, its all very much try and see, they can only ever be guides, never hard and fast rules.

Sam

 

[JamesC]

I had read that excellent article a couple of times before I posted. It would be a good idea to give a formular for Lux per gallon as that is a mesure of light whereas power is just a measure of the amount of electricity consumed, and so can not be used for comparing different types of light. (I'll take my elecrical engineers hat off now : ) )

The problem with using Lux and also Lumens is that they only measure the light in the green spectrum, ie what we see best, and not the blue or red parts of the spectrum. So if you had a tube that emitted a lot of light in the red spectrum it's Lux figure would be a lot lower than one mainly in the green spectrum even though it may output more light. Lux is a great way of measuring light for say an office but for an aquarium it doesn't really work.

This topic has come up before and we always seem to end up with the 'watt per gallon' rule working best as it is the simplest for people to understand when they are starting out.

James