Updating the WPG rule (theory)

[Wizzard~Of~Ozz]

I've noticed more and more people are using Watts from a CF to equal 1WPG.. The way I figure these numbers are.

1 W CF bulb = 1.75W towards the WPG rule
1 W T8 bulb = 1.58W towards the WPG rule
1 W T12 bulb = 1W towards the WPG rule

I think this is the most effective way of doing things. assume 1W CF is anywhere near 1W T12 is an understatement.
--------------------------------------------------------------
(supporting math)
CF = 100Lumens / Watt
T8 = 90Lumens / Watt
T12 = 57Lumens / Watt

the WPG rule is based closely to 57Lumens / Watt
so 90/57 = 1.58 WPG for T8 and CF leading by 1.75WPG
--------------------------------------------------------------

There was discussion before about how the WPG is outdated.. I think this is more true then you know.

So for equal lighting

on a 55Gal tank, 200 Watts of T12 (5 bulbs) can be equaled with 128W T8 lighting (4 bulbs, save 1 bulb.) or 114W CF lighting (2x55w, save 2 bulbs.)

Does this seem like something that is reasonable?
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edit:
Well, on my "crusade" I've finished most of the typing.. hopefully it shows the major differences and can help some people.

Here is the page so far

 

[fishygurl]

Makes sense to me, but what about t5 lighting?

 

[rich311k]

If you are right and your math makes sense. I have over 6 watts a gallon on my tank. Interesting and could explain a few things.

 

[Wizzard~Of~Ozz]

Fishygurl. T5 is a straght CF. (or more accurately, a CF bulb is a bent T5 to reduce it's footprint)

 

[Purrbox]

Actually T5 isn't CF. They may work out the same math wise (I have no idea) but they are not the different terms for the same lighting.

T5 Fixtures

CF Fixtures

 

[Wizzard~Of~Ozz]

Fixed my description of a t5 bulb. the fixtures may be different, but I can assure you those bulbs are virtually identical.

November 18, 2005—The Sylvania 28-Watt Dulux L Supersaver T5 compact fluorescent lamp (CFL) is the newest addition to the company's expanding line of compact fluorescent products. The Dulux L Supersaver lamps are high lumen, single-ended T5 twin-tube lamps that provide a lumen output similar to 4-foot linear fluorescent lamps, yet are half the length, says Sylvania.

 

[Lonewolfblue]

So, is this how I would calculate my w/g on my 26g?

65W CF
26G tank

65x1.75/26=4.4w/g

Would this be correct, approx 4.4w/g?

I currently only have java moss, which is doing awsome. I have no CO2 injection, I suppliment Flourish Excel daily, and Flourish Trace twice a week, and Flourish Iron once a week. And I have no algae problems, nor green water. All's looking great.

 

[Wizzard~Of~Ozz]

Yes. Now out of curiousity, do you use Co2 on that tank? is there a fair bit of algae? Excel maybe?

 

[Lonewolfblue]

I currently only have java moss, which is doing awsome. I have no CO2 injection, I suppliment Flourish Excel daily, and Flourish Trace twice a week, and Flourish Iron once a week. And I have no algae problems, nor green water. All's looking great.

 

[Lonewolfblue]

In fact, the ugly stuff that was growing on the java moss is almost gone now. Used to have this grayish stuff growing on it when I had the original lighting, but now the java moss is very green. Loving it.

 

[Wizzard~Of~Ozz]

hmm, should be interesting to see how your 75Gal does with the equivilent of 6WPG over it..

Interesting about your dosing on that tank. it must have some fairly level nutrients.. or the CAE are still doing well

Green water is caused by 2 things as far as i can tell. High PO4 or low NO3 relative. and excessive light. your nitrate to phosphate level must be in good check.

 

[savga]

Wouldn't it be great if there were such a thing as a cheap underwater light meter, then we could real standardize lighting requirements in foot-candles or lumens or whatever. Just daydreaming.

 

[Lonewolfblue]

The CAE is doing well. Just been chasing the dwarf gouramis lately. I can't wait to get the plants. Will place my order online tomorrow, that way it gets processed first thing Monday morning, and shipped. Currently in the 75G, no plants and the water is tea colored from the driftwood. Looks pretty good under the lighting. The 2 front bulbs are 6500k bulbs and the 2 back bulbs are 12000k bulbs. Have been debating on whether to replace the 12000k bulbs with 2 more 6500k bulbs. My 26G is a 6500k bulb. Looks awsome.

 

[Lonewolfblue]

hmm, should be interesting to see how your 75Gal does with the equivilent of 6WPG over it..

Interesting about your dosing on that tank. it must have some fairly level nutrients.. or the CAE are still doing well

Green water is caused by 2 things as far as i can tell. High PO4 or low NO3 relative. and excessive light. your nitrate to phosphate level must be in good check.

Well, with PWC's, I keep my nitrates below 20ppm. Usually about 5ppm after the PWC. Then at about 20ppm when I do the PWC or a little above. I haven't checked the phosphate level yet to see where it is. Might do that tonight out of curiosity.

 

[Lonewolfblue]

Well, I did the tests on my 26G, here's the results....

Temp 79.3
Ammonia 0ppm
Nitrite 0ppm
Nitrate 7ppm (color to me looks half-way between 5ppm and 10ppm colors) Did 20% PWC earlier today.
Phosphate Just over 1ppm. No where near 2.5ppm. So I'd say about 1.25ppm.

Test kit used, Hagen Master Test Kit

 

[sherry]

wizzard if this is right, I also have way more than 3 wpg.. I guess I have to mess more with ferts to get better reds.

i ahve a 96 cf quad over 35 gallons (think 30 gallons after substrate)

do you think the quad bulb lessens teh effect tho?

 

[Wizzard~Of~Ozz]

It has more to do with the intensity. There is also more to the WPG rule then it takes into account. so 6WPG according to the calc is not always a bad thing. the depth of the tank has some play too. someone posted the calculation that takes into account the distance from the substrate.. and I noticed when I used that calc. my recommended WPG was somewhere much higher then 4WPG to get the equivilent of "high light".

The purpose of this was more to address the problem some are having by trying to hit 4WPG of CF lighting and not taking into the account that CF bulbs are 175% more lumenous then the bulb the "WPG Rule" was based on.. however, with that, the WPG was also wrong to start with since it doesn't take into account the height from the substrate, the spectrum of the bulb etc.. most people that are hitting 4WPG are doing it on 20Gal or less tanks, they tend to be very short (sub 18") and that is where the problem comes in.

As for bringing out the reds. I can tell you it is not always lighting related. with the exact same light over a tank (same intensity), I have had rosenervig that was very red, and now it's very green.. 2 things that changed. I removed the actinic 50/50 bulb. I also allowed the nitrates to run up a bit higher.. So either the absence of actinic light or the high trates cause the plant to lose it's red..

I'll try to write up a better article with more variables taken into account. I've learned a lot about lighting.. figure it's time to apply some of it. Also, Philips is sending me some spectral outputs for some of their "home depot" brand lights. (Daylight Deluxe and Natural sunshine). it should be interesting to see what else is in the documentation and how they compare to the bulbs that are 10x the price at the LFS..

 

[czcz]

Just feedback/thoughts.

I've noticed more and more people are using Watts from a CF to equal 1WPG..

A watt is still a watt though, and so WPG is the same. Of course your point is with relative light output, and so you should move forward in posts off-thread with "lumens per gallon," or perhaps "relative/equivalent NO WPG" or something.

The way I figure these numbers are.

1 W CF bulb = 1.75W towards the WPG rule
1 W T8 bulb = 1.58W towards the WPG rule
1 W T12 bulb = 1W towards the WPG rule

I think this is the most effective way of doing things. assume 1W CF is anywhere near 1W T12 is an understatement.
--------------------------------------------------------------
(supporting math)
CF = 100Lumens / Watt
T8 = 90Lumens / Watt
T12 = 57Lumens / Watt

the WPG rule is based closely to 57Lumens / Watt
so 90/57 = 1.58 WPG for T8 and CF leading by 1.75WPG
--------------------------------------------------------------

I suspect your sample for these measurements are too small (1 or 2 bulb ratings?), and so you should increase it for more accurate data (if moving forward with lumens), as using 3 sig figs with the current data is unsound. Notice just playing with lumens/watt on this chart yields +/- 10% with almost any two bulbs of the same type: http://www.aquabotanic.com/lightcompare.htm Also notice their efficiency rating (rated vs. theoretical max) is typically higher for CF than NO, including T8.

most people that are hitting 4WPG are doing it on 20Gal or less tanks, they tend to be very short (sub 18") and that is where the problem comes in.

Rex Grigg proposes this is not because of tank height (he does not believe tank height to matter with a good reflector), but because there is a minimum amount of light required for "med" or "high" light. His idea of a Minimum Light Threshold is sound, though his explanations at times are not, ime. (I have only kept small tanks.)

krap101 linked this today, and most importantly it uses analysis of known, functional tanks: http://www.fitchfamily.com/lighting.html This is the most interesting and meaningful support for minimum lighting threshold I have seen, though it does not mention lighting type.

Anyway, let's test. My high-light 8gal has 2x13W CF and 1x20w NO. I came to using this light by trial and error through obervation of high light plants. (There is also light from a 23w spiral screw-in CFl on the side for a nano, but I am ignoring it.)
Using your calcs above for equivalent NO WPG
(26w CF * 1.75w NO equivalent/(w CF)) + 20w NO = 65.5w equivalent NO

The fitchfamily.com derived Amano calc gives 59w. Pretty close.

(If anyone has Takashi Amano's books, could you post if he usually uses NO or CF on his tanks? I had assumed he hardly used NO.)

with the exact same light over a tank (same intensity), I have had rosenervig that was very red, and now it's very green.. 2 things that changed. I removed the actinic 50/50 bulb. I also allowed the nitrates to run up a bit higher.. So either the absence of actinic light or the high trates cause the plant to lose it's red.

I do not understand how you got equal lighting intensity after removing a 50/50 bulb. You replaced it with a a full spectrum bulb of the same type and 50% rated watage of the 50/50bulb?

I like actinic over planted tanks for aesthetics too, but would put money on low NO3 being responsible for the reds, assuming all other variables were static.

I'll try to write up a better article with more variables taken into account.

Suggest you also note that all calculations moving forward are with the assumption of a 100% effective reflector, new bulbs, and so on. Use large samples for your analysis!

Excellent thread! FWIW, I am of still of the opinion that WPG's usefullness ends whereever CO2 is necessary, and the rest is tweaking to get past the threshold of high light, if wanted. I suspect that a full analysis of lighting and all its variables -- very small and high volume breaking the rule, tank surface area, height, reflector quality, glass tops, and so on -- makes a one-size-fit-all standard unlikely. Instead, it is better to tackle light with experience and trial and error, as most tackle stocking,

 

[CGGorman]

Wouldn't it be great if there were such a thing as a cheap underwater light meter, then we could real standardize lighting requirements in foot-candles or lumens or whatever. Just daydreaming.

There is. Milwaukee makes one. http://www.milwaukeetesters.com/english/products/economy_portable_meters/SM700.html

Only the probe is waterproof. I've been kicking around buyuing one just for giggles...

 

[CGGorman]

Very interesting thread. I didn't realize PC bulbs were so much more efficient than NO. I'm running 2x 96W PC over a 25" deep 70. I assumed I was running around 2.75 wpg. Sounds like I'm actually pushing 4.8 wpg.

I have two of the Amano books at home. I'll try to remember to look at what he was using. Walstad uses some funky scientific measurement for her lighting section. Something "photoequivalents per square meter" or something. She even admits to not fully understanding the measuremement of lighting intensity.

I may have to pick up that Milwaukee tester just out of curiosity.