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Re: light & red plants & more on lighting
> 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
> water types(very soft with added KH/GH to about 4 each and my water which
> 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
> 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?