Why do we measure still by WPG?

[Codefox]

Really after reading the information, why aren't we measuring by lumens? It seems to me that just going off of straight WPG is extremely inaccurate. I went with 2 WPG on my 55 gal based on that but my two bulbs will probably be putting out at least 9,000 lumens. At 2 WPG I'll be the equivalent of 3 WPG of NO bulbs.

I know this is all covered in the stickies but most conversations here still seem to focus on the WPG rule. I think maybe we should consider a new 'rule of thumb' scale for PC bulbs since they seem to be popular. Cause I know all of the different bulbs and terminology really had me confused when I first started thinking about plants

 

[Drocnoc]

I think it is because all bulbs display Watts while it can be difficult to find the lumen output of a specific bulb.

 

[Codefox]

Yeah, but when someone comes in and says they have 2 WPG of a PC light and is told that's a medium lighting situation...that's really not at all accurate. It's most likely close to a high light output.

 

[czcz]

I do not mean to be a contrarian, but lumens are not perfect either. Whole numbers with WPG are nice and accessible, there will always be conversation and members more interested in more advanced metrics, and in the end it is all experimentation anyway. I am interested in new metrics as well, but think it ambitious to target a new rule of thumb. Some bookmarks with interesting metrics that are worth studying, if you have not already:

http://www.aquabotanic.com/lightcompare.htm
http://faq.thekrib.com/plant-lighting.html
http://rexgrigg.com/mlt.htm

 

[Drocnoc]

I totally agree, but i think its easier for the newbie to understand WPG versus Lumens, And with NO the WPG rule works well and most newbs only have NO. Plus its also easier to explain WPG to a new aquarist.


Its kinda like the 'Inch of Fish per Gal' rule, its not a set in stone rule but good for the beginner.

IMO

 

[Codefox]

The inch of fish is a good example...I do get the point. I just think that it would be helpful to at least clarify that you're talking about NO lights vs other types. Thanks for the links too

 

[czcz]

If you are brainstorming, perhaps the best way to start would be to survey the members here who use PC/CF for whatever criteria you think is relevant. I think it would be best to use the guidelines of the above articles and see what works best, using which plants are grown as the standard. FWIW, Dennis Bednarek and Hardjono Harjadi's paper hits my small tanks' requirements almost exactly, but I am using a mix of CF and NO over most of them while calling a watt a watt.

I just think that it would be helpful to at least clarify that you're talking about NO lights vs other types.

If you did a survey, I would bet that most of us agree

 

[Meredith]

From a beginners prospective, I didn't even know to look for lumens. I know how many watts I have though. As with any "rule of thumb" I think most people realize that it is a starting point and other factors can be taken into account. Its like the 1 in per gallon rule. Its a good BASIC rule for most beginners but by no means is it the ONLY rule.

 

[Codefox]

I didn't know to look for lumens either but there's a few things to keep in mind. I don't think most people wanting to keep plants are new to the aquarium hobby. I've been keeping fish for at least a decade. I'm sure most of us can handle additional info

Thought from what I read it's obvious there's still a lot of unknowns...I'll just have to get a feel for it.

 

[Hoovercat]

I started keeping plants roughly 6 weeks after I started my first aquarium.

 

[Codefox]

I spent most of my early years keeping cichlids...I couldn't even keep plastic plants in the gravel

 

[hashbaz]

While I agree that watts are not great to use, lumens are not great either - and not just because they are harder to find.

Lumens are based on human perception - not light energy output. We humans perceive yellow light as being brighter, but plants need red and blue. Therefore a yellow light with 3000 lumens might give off less usable light than a 2500 lumen red-and-blue light.

Figuring out the actual usable light intensity reaching the plants is extremely complicated. So we make a whole lot of simplifications - resulting in a grossly inaccurate "rule of thumb". "Watts/gallon rule" or "Lumen/gallon rule" are both inaccurate, but watt ratings are readily available, making the wpg rule the easiest "rule of thumb."

 

[chrism]

My question would be... why dnt we use watts per litre?

is it US Gallons or UK Gallons... perhaps the WPG rule should be changed to WPUSG / WPUKG

nah seriously, i think it's a good starting point, and it's best to keep things simple esp for the newbies to fish/plant keeping. From my point of view (i've no where near mastered fish or plant keeping) it's just a generalisation, a rough idea that if you've only got 1 wpg you'll only be able to grow low light plants, or 2wpg your on the verge of needing CO2 etc i am aware that spectrum & depth & various other factors will effect how much effective light i really have... so i take that into consideration.

after all when you buy plants, it doesnt say on the label needs 3562.4 lumens or even 2.6wpg any advice jst says medium high or low!

 

[dskidmore]

So, anyone going to make a stab at a WPG rule of thumb for HO, VHO, PC or MH lights? As stated, the current WPG rule only applies to NO, there should be a similar set of principals for each of the major lighting types.

 

[Jchillin]

We interrupt this thread for a special bulletin. FWIW, most of the issues contained in this thread was covered here: http://www.aquariumadvice.com/viewtopic.php?t=55461. If anyone is interested, take another look at it.

 

[malkore]

Most people don't have a Lux meter, and thus we use the best option available.

Besides, I've seen glosso grown perfectly in 2wpg of NO lighting, and seen it fail in 3wpg of power compacts.

Light is a driving force, but if other things aren't up to par, no amount of light can fix it.

 

[Codefox]

There definately is a lot to think about. I know that most of it is covered in that thread and I did read it...it just isn't a huge issue dealt with there and there definately many many things to consider when growing plants. I think even more so than fish. With fish it's relatively simple because they're biologically similar to us :

Clean living area, adequate room, sufficient food and friendly tankmates. That's easy to conceptualize. But when you look at plants you need to think of lighting and a lot of extra equipment. With plants you don't need food so much as the actual nutrients. This is probably why some people never really get their plants to live...there's a lot that goes into it.

And I don't think we neccessarily need to make the 'rule of them' that much different than general. If I said I wanted a med-light tank and said I was using 2.0 WPG of CF lighting, I think it'd be enough to know that I'm really pushing the border between med & high light. Not only for equipment but also for what plants I'm going to look into.

Anyway, just trying to learn all I can, and just thought I'd put my view out there of all this. If it wasn't for you guys I'd probably be trying to grow my plants in my .66 WPG of NO lighting as recommended by the LFS

 

[BrianNY]

This is a very interesting discussion. I think the reason lighting is stated in WPG, is because it's the simplest to understand. When we purchase bulbs for our homes, most bulbs are expressed in watts, so people are famaliar with the output and usage.

 

[czcz]

So, anyone going to make a stab at a WPG rule of thumb for HO, VHO, PC or MH lights? As stated, the current WPG rule only applies to NO, there should be a similar set of principals for each of the major lighting types.

As a general statement, surely anyone running HO, MH or VHO in a planted tank is looking for high light, and high light types generally do not care too much about specific wattage because they are past the threshold of "high light." Every now and again you will see someone mentioning they run +5wpg of CF over a large tank, but they never mentioned it before because the only variables they worry about are CO2 and ferts, for example. WPGs biggest strength is it tells newcomers how far they can go before they need CO2. It does not need to be extended to other lighting types.

Only my opinion and observations, of course.

 

[Jchillin]

If it wasn't for you guys I'd probably be trying to grow my plants in my .66 WPG of NO lighting as recommended by the LFS.

Indeed, the LFS is definitely not the locale to accept planted tank advice. Not enough "know-how" there certainly.

WPGs biggest strength is it tells newcomers how far they can go before they need CO2. It does not need to be extended to other lighting types.

I agree...we can certainly distinguish between someone saying "I have 65w..." and "I have 80w...", we already know that NO stops at 40w.