schaadrak

I have a 12gal Eclipse that will be a NPT here shortly. It comes with 13W CF already in the hood and I was thinking of adding another 13W to it which would bring the WPG to about 2.17. Is that too much, or is there some flexibilty with the WPG rule?

onemyndseye

Well... this is a loaded question ...

On the rigidity of the WPG rule:
the WPG rule tends to start breaking down the closer you get to 10G and below because there is a minimum amount of light needed to activate photosynthesis. For an extreme instance, if you took a 1G tank and put 5Watts of light over it effectively giving you 5WPG you would probably be very discouraged to find that nothing will grow in your 5WPG "high light" tank because a 5Watt light just doesnt pack the intensity needed to kick off photosynthesis.

WPG is a "Rule of Thumb" so to speak

Now all that being said - 26Watts of CF's should be plenty for a NPT this size.

Those Eclipse systems look so nice too

Good Luck!
-Justin
One Mynds Eye

schaadrak

I figured there was more to it than just that.

Let the modifications begin!

iris600

I'm currently facing a lighting conundrum as well. I have a 35 gallon hex that is quite tall. I know that the taller the tank, the more light loss is experienced. I can either put 1 or 2 55watt 5500K bulbs over the tank.
Which decision is better for el natural knowing that my natural lighting, even near the best window in my apt, is minimal?

Peter66

To revive this one. Is there a specific reason why plants that do well in a normal tank with less than 1w/Gallon would not make it in a NPT?

Spidergrrrl

I have somewhat of a vested interest in this thread too, as I just bought the same system (set it up this weekend!).

I was researching how to retrofit the hood with additional lighting, but since I'm not very good at DIY projects, I got easily overwhelmed and intimidated. In the end, I decided just to see how things go with the default setup.

So, please keep us updated.

Zapins

onemyndseye: very good explanation, I hadn't heard all of that in one place before. Seems like all one sees is glimpses of info that makes sense around the web, but nobody sums it up nicely like that.

Peter66: what onemyndseye was getting at was the fact that wattage (used in the watt per gallon rule) does not have much to do with how intense the light is. wattage is just a measure of how much electricity (in joules/second) is passing through a particular device (be it a stove, a fan, or a light) each second. Since wattage is just a measure of the power going through the device, it does not tell you how efficient the light is at turning that electricity into usable light. Thus, if you had a 60w incandescent light bulb and compared it with a t5 or power compact light of equal wattage, you would find that the 60w incandescent would not be able to grow plants very well, simply because most of the watts passing through the bulb are used to make heat - not light. The T5 and PC lighting are much more efficient at turning electricity into light and will therefore be brighter and throw off more light per watt than the incandescent bulb will.

For this reason, Peter66, it is possible that plants can do very well in a tank that has 1 wpg or even less. In fact, if you had a light bulb that somehow turned 90% of the wattage into light, and had equally good light spread, then you could adequately have a high light 125g with a very low wattage bulb (maybe ~30-45w).

Because it will take many more low-intensity bulbs and much more $ via electrical costs to light a tank, people usually invest in quality lighting and reflectors and do not usually use lower efficiency bulbs like incandescent lights.

Also, in case you were wondering why people still refer to (and why it is still usable information to know) how much light they have in wpg terms, its because most people out there have higher efficiency lighting that have about the same light/watt output. For example T5’s and MH are pretty close together, even PCs are pretty close. So it makes less of a difference when talking about how much light we have, if all our light fixtures are all about the same intensity.

JeffLL

Give or take, for each class (not size, configuration or pins) of florescent lamp, such as standard, high output (HO) or VeryHO, the light per watt is comparable. It's also about output per size. The VHOs simply use more electricity to make more light, which may or may not be converted more efficiently. Age probably reduces output by much more than the difference between the the best and worst performers across ALL florescent offerings.

To sum it up, the rule of thumb is broad enough to say 1.5 - 2 Wpg of florescent lighting is the starting point. I am sure that there are plenty of people streaming in over 10Wpg.

Note that I will be using a GU10 or MR16 (low voltage) incandescent halogen track lighting mini spot lamp to warm a 'sunning' rock for my turtle(s) in my paludarium.

_______________________________________________
If you don't vote, you can't complain. Take your head out of your tank for half an hour and make a difference. The act and privelege of voting is what makes any democracy strong.

Peter66

Thanks for the reply, I use philips aquarelle with reflectors so I got suffiecient lighting for my plants in my current setup. Can I assume that my crypts and swordplant will not need more light simply because I change to soil under gravel?

ruki

Think your VHO information is dated. That was a true statement a while back, but from today's perspective VHO is an old, inefficient technology that requires significantly more watts to get less light than the new choices that came out in the past decade. It's so 1980's

You can get up to twice as many lumens per watt from the most efficient T5 bulb compared against the old T12 tubes. Between these are T5 HO, Power Compact, and 2x overdriven T8s.

Then you have reflector issues. PC tubes are folded, so they interfere with the reflector, so they aren't even close in light output sent down into the aquarium per watt when compared with a good T5 HO fixture.

It's one of those +/- 50% things. The watts per gallon rule is a convienient simplification when one doesn't want to think about all the above. It's also used by PC fixture vendors to gloss over the fact that using bent tubes for linear aquariums really doesn't make much sense now that T5 HO is here

There are some incomplete charts demonstrating this: http://woo.gotdns.com/Aquarium/CalcL...h=18&Length=48
Luminous efficacy - Wikipedia, the free encyclopedia

Fortunately for us, most plants are highly adaptable. It doesn't really matter too much unless you have racks of tanks and want to reduce a quite large electricity bill.

You will do fine with many choices.

With global warming concerns and electricity prices likely rising in the future one can make an argument to use T5s or T8s in new fixtures.

This is my standard "watts per gallon" rant from the lighting forum