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Re: light & red plants & more on lighting
Tom wrote:
> I have nice red Cabomba and Rotala at 2 watts a gallon. 2x40 watt bulbs over
> a 40 long tank.
> Cherry red all the time. It ain't da light. Neil has some blood red Rotala
> macrandra at the same amount of light.. possibly less. I have wallichii at
> about the same lighting that you have.
> Back off the NO3 levels and see what happens. I suspect you'll get better
> colors. Several folks have been finding this to be the case in different
tap
> water types(very soft with added KH/GH to about 4 each and my water which
is
> KH5/GH9). Both tanks have less light than you have.
> PC's will add more light for a reasonable cost. 2-55 watts would do plenty
> for your needs. Check out A&H for more info.
I checked into compacts. I can't retrofit my light strips, according to Kim.
I'd have to start from scratch.
>
> As far as NO3 levels, I just add more food and no KNO3 but still add K2SO4.
> Growth is slower but better looking colors. Perhaps its the NH4+/NO3 ratio
> but its a complex cycle I'm betting.
> I think a lower NO3- level and a higher NH4+ might help this. How much on
> either? Likely 1(or less perhaps)-3 ppm on the NO3 and it would be hard to
> get any NH4+ tested since the plants get it first I would bet. I'm not
> certain about this idea as of yet but enough to fiddle around.........
Wouldn't an unbalance here reflect in lower growth rates, as opposed to leaf
color? With enough co2 pumping, I get extremely fast growth, and sometimes
even get that *leggy* look (like it grew *too fast*). Mainly, my complaint is
too much green, and not compact enough for my liking. During a LOA, the co2
was turned off. Although somewhat more compact growth resulted, the plants
were looking on the unhealthy side when I returned. (This was a downer--I was
eventually hoping to turn the CO2 off once I got the tank the way I liked
it). Seems like some plants need the added CO2.
> But its not your light/substrate. I also noticed that lower fish load tanks
> tend to have the redder plants as you can over feed these without fouling
> the tank and also be NO3 limited but not absent. That can be a fine line
> between absent and a little NO3 so be wary.
>
This is a tank that's been left for the most part to 10 small fish (neons &
cardinals), a few feeder guppies, and 2 or 3 glass shrimp that do some
cleanup. If anything, the load is too low. This makes sense, then, as I'd say
the NH4 is near to non-existent for the plants' use. Anybody ever tried
fertilizing with ammonia? And I believe in an earlier post you talked about
MgS04 making a difference in red coloring?
and Cathy replied:
> that you can't
> just flatly state that you can grow any plant, or any bright red plant
> (sorry Tom Barr), with 1.5 or 2 watts per gallon, without qualifying
> exactly what the lighting conditions are. Tank height and size,
> water surface clarity, reflector, ballast, bulb type and age all come
> into play. Thus, when Tom says he can grow any red plant in low
> light and it ain't da light, I have to ask, what exactly are your low
> light conditions? They may truly equal much more than low light.
> The rule of thumb about watts/gallon really falls apart at this level.
I was wondering this also. A 20 gallon long grew reds much better than this
tank will, a 29 high, at the same watt/gallon ratio. This is a 12 inch tank
vs. approx. 18 inches. A standard 55 gallon (another one I'm having some
trouble with) is a bit over 20 inches.
>
> I will just add my anectodotal comments. There's no doubt in my
> mind that light plays SOME part in the reddening of SOME plants.
> Hygro polysperma, for example, only develops a reddish tint to the
> leaves under strong light. You can dump in all the iron you want but
> leaves that are shaded will grow green, and leaves in bright light will
> have a pink tint. Ditto the Tropical Sunset variety. Unshaded leaves
> are much more vibrant than shaded ones, which generally don't
> even show any pink. Same with red Ludwigia repens. I have to
> believe that in these cases, it IS the light. <snip> SOMETIMES it's the
> light.
>
> In the latter tank I recently replaced 2
> coralife 50/50's (there for color balance with the trichromatics) with
> Ultra Tri Lux (a fine bulb!) and the difference in light level is marked.
> The plants notice it too. It's still 3 watts/gal, but it means
> something entirely different than it did before. I like high-light tanks,
> but they certainly do require careful monitoring as things happen
> quickly in there.
>
This is what I'm after . . . stuck with 2 double strip reflectors on this
tank, what is the best I can get with what I got? I need a couple of good
bulbs that will improve on lighting conditions. What are the specs on Ultra
Tri Lux? I would think it's the lumen count that we're looking for? and to
some extent color spectrum, but there seems to be contradictions on the blue
& red (the golden rule) vs. green & yellow spectrums.
Diana Walstad reports in her book about an experiment where 4 different light
bulbs were compared, by photosynthetic rate (judged by level of oxygen
produced) on elodea. A full spectrum (Vitalite), cool white, warm white and
daylight bulb were compared. 2 bulbs were placed over the plant, in various
combinations. 1 cool white, with 1 vita lite produced the best results,
followed by 2 cool whites. 2 Daylights fell in the middle, and the 2 warm
whites fell at the end. She reports that cool-white gave off 13 % more
photosynthetic light than vitalite. The argument is that aquatic light
differs from terrestrial light because water absorbs red light, and DOC
absorbs blue light. This leaves green & yellow for photosynthesis, which
contradicts everything I've read thus far. This was further complicated
because she speculated that the cool whites had a slightly higher light
intensity than the others. It's difficult to glean anything from this with no
further info about the bulbs, but maybe somebody out there has more to add?
Sylvia