PAR meter apps, android and iOS

[MichaelJ]

Why is it that people try and optimize CO2 and micro/macro ferts and then go on with the doktrin of plants are adaptable and can handle almost any light we provide them with?
Looking in the literature it is clear that the importance of mosts parts of the solar spectrum plays some role in plant growth/development.

For sure, I agree. Looking at the absorption curves and the photosynthetic rate curves for plants it's pretty clear what the preferential wavelength bands are and where they pickup their energy for photosynthesis. The choice of light is certainly not inconsequential, but I will submit that for most practical purposes most modern-day adjustable aquarium light fixtures will offer a decent enough coverage along the 400-700 mn PAR range to make them suitable for plants as long as you keep the light temperature fairly balanced towards daylight. If that wouldn't be the case, I think a lot of hobbyists around here would be in trouble because of they light. The light related issues we see around here are overwhelmingly about excess light intensity.

Because PAR without the knowledge of the spectral powerdistribution is not that useful. I have been experimenting with lights over the last 5 years and found that the closer I can get the spectral powerdistribution to that from the sun (within the 380 nm to 760 nm range) the less intensity I have needed for getting good growth.

I do not doubt that that the distribution can be optimized to increase yield at a lower intensity. It would be interesting to learn more from you about this. I think you should post about your methods, equipment, experiences and results.

Cheers,
Michael

 

[oreo57]

Personally, this is kind of a big can of worms.
Spectrum can influence everything from morphology to nutrient content.
Also can be species dependent on the effects.
Also my most fun thing to think about.
Below the water the environment does a 180 where high blue ratio would mean low light conditions and high red would be high light conditions.
Exact opposite of the above water situation.

Unless one has a very specific goal in mind regarding a group or a specific species I'd not chase spectrum.
Well I'd chase it more for my own visual enjoyment.
That said If I needed to pick ONE led for all my needs it would be one that, as mentioned above, was a natural light type led.
Bridgelux EB COB.. 6500k
Grey is sunlight

BUT for those that would want to do something like highlight red plants the "rules" sort of change.
It would deviate from what one thinks of as "natural" a bit.

Fun read......which has little to do with underwater plants.
But sort of fleshes out the broad area.
LED Illumination for High-Quality High-Yield Crop Growth in Protected Cropping Environments

Arbitrary control of the intensities of LED illumination spectral components enables the continuous optimization of the illumination spectrum over time, typically required in real-life scenarios. For example, far-red can be an effective non-chemical means to control plant morphology [144]. However, with short exposure to far-red, the mechanisms responsible for increasing the plant biomass are still not well explored. They may be attributed to hormonal changes and transpiration. Cope et al., 2013 indicated that the optimal illumination spectrum for plant growth is likely to change with the plant age and stage and environmental conditions [145].

Of course there is the discussion of the
"missing" spectrum i.e UV/IR but for the most part I fail to see why the majority would need to chase it
Or the fact that one goal seems to be to "improve" on nature..in some manner not just follow it.

 

[MichaelJ]

Personally, this is kind of a big can of worms.
Spectrum can influence everything from morphology to nutrient content.
Also can be species dependent on the effects.
Also my most fun thing to think about.
Below the water the environment does a 180 where high blue ratio would mean low light conditions and high red would be high light conditions.
Exact opposite of the above water situation.

Unless one has a very specific goal in mind regarding a group or a specific species I'd not chase spectrum.
Well I'd chase it more for my own visual enjoyment.
That said If I needed to pick ONE led for all my needs it would be one that, as mentioned above, was a natural light type led.
Bridgelux EB COB.. 6500k
Grey is sunlight
View attachment 217563

BUT for those that would want to do something like highlight red plants the "rules" sort of change.
It would deviate from what one thinks of as "natural" a bit.

Fun read......which has little to do with underwater plants.
But sort of fleshes out the broad area.
LED Illumination for High-Quality High-Yield Crop Growth in Protected Cropping Environments



Of course there is the discussion of the
"missing" spectrum i.e UV/IR but for the most part I fail to see why the majority would need to chase it
Or the fact that one goal seems to be to "improve" on nature..in some manner

@oreo57, I very much agree with pretty much everything you said above. However, I really want to learn more about @Aquahorti experiences on the matter.

Heck, I may even join the optimal spectral distribution team... just as I joined the lean fertilizer team after being extremely skeptical initially, or the no bio filtermedia team or the duckweed index team... (those ones didn't take much persuasion though) ... well, as long as it works! right..

Cheers,
Michael