Algae and aquatic plants can use both blue and red wavelengths and
everything in between.
Algae and plants both live and grow in water less than 3 feet, the
issue of blue wavelengths are not that great when dealing with the
average tank.

Turbidity will remove all wavelenghts not just blue and this is common
in a number of natural systems. Tannins will selectively remove
certain wavelenghts.

Both algae and plant both possess Chl a as their final energy transfer
molecule before splitting the water for e-'s and H+'s. There are two
special Chl a's called *P680 and *P700.
Chl b, c, d, and all the other pigments like beta carotene etc only
use wavelenghts that are higher energy (shorter wavelengths). These
lose energy and relax down to the lower energy levels and are funnels
into these final transfer molecules. Lower than 700 nm are not usable
by plants or algae. You cannot go "uphill" so to speak.

All the enegy from these assessory pigments are transferred via
resonance to the reaction center Chl a molecules.
Some bacteria can use longer waveleghts and have only a single
reaction center molecule instead of a pair like Chl a.

But algae and plants can alter and change their ratios of these
pigments to catch whatever is being offered.
You can change the colors but you often will get the same algae or a
new
species to fill it's place.

Blue light responses in plants allows more CO2 since the stomata open
even larger when the plant is exposed to blue and better growth occurs
and it looks better to our eye if the color is well balance.

You get a more efficient watt to quantum yield of plant growth if you
stay close to the Chl a's spectrum but, the plant can handle most
things you throw at it. Same goes for the algae. They are _extremely_
similar biochemically.

You gain no advantage by using so call plant bulbs that "reduce
algae".
If they can show practical evidence in a plant tank this occurs, I'd
love to see it.
Otherwise it is pure speculation and I think , BS.

I've used all sorts of colors and have found nothing that would
indicate a better final steady state that give any advantage to the
plants vs the algae.

After about one month both algae and plants have adapted to whatever
color temps/wavelenght you have provided for them.

At the light level, algae and plants are too close to make any use of
this and algae can live on a order of magnitude of less light than
higher plants. Waste of money IMO/IME but what your eyes precieve how
the plants appear in certain light color is something to consider.

A 10000K 40w bulb will grow plants. But you get less useful light
since the higher wavelenght will need to lose some energy before it
makes it down to the reaction center. The excess energy can be given
off as fluorescence, heat etc. A warmer red colored bulb with a blue
spike will give the best preformence but the light will all funnel
down to the same place. But as far as useable light energy, the
660-700 range is great watt for watt. Looks ugly and the blue spike
will open stomata more and make things look better also.

5000-6700K looks good, Triton's 7500K look good and the 8800K bulbs
look good also. I use 4300K bulbs in MH's and also 6500K's.
Get temps in these ranges and your fine. Good color for your eye and
the plant's needs.

Regards,
Tom Barr