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Re: [APD] Aquatic-Plants Digest, Vol 25, Issue 50

>Most people don't care about the nitty-gritty details, and that's 
>absolutely fine. You appear to be one of them. 
I am often underestimated, which is better than being overestimated.
 I applaud the graphs and the correlation, I do and am interested in it.
I do play devil's advocate often, then I'll play sucker and sold my soul for something. But we need both to find that all important middle ground.
Rather than an attack directed towards you personally, I focus on the plant issue. That I will attack with extreme malice depending on what it is or immediately embrace and explore. I do not which way I will go, but I tend to go both ways on most issues to get a sense of both prespectives.   
>What I don't understand 
>is why you are belittling the idea that hypotheses should be tested 
>before being represented as fact.

Being critical and belittling are two quite different things and it's(light and it's measurement) an issue I've discussed on this list oh...........no less than a dozen times with some folks sharper than needles. It's an issue I've written papers on, it's an issue I've written articles for this hobby on also, and not too long ago. I know the ins and outs of this issue fairly well. 
If you desire to do the project and test, knock yourself out. My question to you and to anyone for that matter is what do you hope to gain from this endevor and all this work?
I do not mind doing lots of work if I gain something worthy of my time. Some discussion and thought can save you a lot of grief later. 

>Growing plant X under Y lights doesn't tell us anything useful without 
>further information.
Such as distance, lamp age, type. All things folks can do consistently. Most have cameras and the light meters can be useful for intensity measurements.
But see below about middle ranges, it is quite useful indeed.... and has not failed me to date.
Maybe I've been "lucky" everytime?
 >The only way to find out what is relevant and what 
>isn't is with controlled studies, or at least semi-controlled. 
Here's a set up I did some years ago(10?). 55 gallon tank, ample CO2(30ppm+), high nutrients(therefore non limiting). Frequent water changes to maintain nutrient ranges, remove organic fractions etc, high plant density.
One one side of the tank, I used 4x 20 w lights, the other, 4x 20w lights.
Later, I upgraded to 2 x 55w per side.
You can hang the lights on a chain to rise and lower the lights to reduce or increase intensity.
This distance can be measured.The watts and bulb type/age can be recorded etc.
The nutrients/CO2 are the same for the entire tank, we assume that there is no difference due to good mixing(the water is all in the same tank). A camera light meter can work and each f stop corresponds to a change in lumens.
You can easily remove a bulb or a bank of lights to raise or lower the light intensity or color type etc. 
I also posted plant adaptations to different light levels I think back in 2002 or so. 
Plants can and do adapt to light, so do algae. You need to allow time for that to occur also.
>The last 
>thing I would have expected to hear on this list is somebody discounting 
>that idea.
I never discounted a controlled study, I've done them on lights and can suggest a very easy and simple way to do this(see above), not with 600-2000$ or more light meters. There are some back door ways of getting around needing such equipment(such as the need to have test kits for every parameter and using the plants as a bioassay for CO2). 
These methods allow you to hone skills in other areas, many folks still have trouble with CO2 for example or dosing nutrients. The plants themselves are the main focus in this hobby and their health is the goal, so they can be used as a "test kit" bioassay also.
I have some very nice instruments and equipment for water monitoring, I also do this for a career and teach and train others to do this. Even the most controlled study has it's assumptions and limitations. Making sure folks are aware of these and making sure they are good, reasonable and safe is important. Research is great, but good direction/an easier way to answer the question is a wise approach. I hate wild goose chases and I've seen and done more than my fair share. 
I'll ask you this, how is the watt/gal rule bad or in need of change?
It's a valid question before suggesting a more complicated method don't you think?
With nearly 300 species of aquatic weeds and about 50 species of marine plants grown to a very high level over 15 years, I have not heard a decent argument to change the rule to date and I've tried it in practical tank set ups perhaps a hundred or more times over the years. 
The observations suggest the watt/gal rule at 2-4w/gal is pretty good. Unless my eyeballs are lying to me.......the exceptions to this rule are very rare.
The 2-4w/gal range is a good middle range, most plants do well at less w/gal and will do well above this range also. That's why it works, it's a good middle range. So if you have FL's or MH's, this will work well, if you have more efficent lighting etc, you might get away with less, but adding more will also work, with a little effort on the dosing and the CO2.
Which gets folks back to the original issue of control...........if they cannot control the CO2/dosing, then they will have trouble ruling things out like light. 
>Jerry Baker

Tom Barr

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