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T-8 Lighting, Plant/Algae competition
> From: Todd Ellerbee <Todd_Ellerbee.DBS at dbsnotes_dbsoftware.com>
> Date: 21 Sep 95 8:52:16 EDT
> Subject: RE: Lighting
Todd,
> Oops. I didn't mean to imply that I haven't seen _any_ T8 bulbs
> just haven't seen any in the 48" length that I need. The larges
> seen are 36".
The largest selection of T-8 bulbs (or any bulbs, for that matter)
is in the 4 foot length.
> What I have now are Sylvania Octrons, 4100K. The
> 15w Tritons (see below), so the tank went from a pleasantly subd
> tint to garrishly bright green. I've gotten used to it now, but
> to "soften" the color a little.
Oh. So your another one of those people who enjoys the look of a
"purple" plant tank.<g>
Seriously though, you are now talking apples and oranges. That's
not necessarily what the _plants_ like. This is what you,
subjectively, like to look at. IMO 4100K is too low for the kind
of growth I want in my plants. Red end light promotes tall, lanky
growth, while blue end light promotes shorter bushier growth. I
prefer a bulb of about 5000K, but with a spectral curve that
includes light in both the red and blue ends of the spectrum.
THEN, I also like the middle filled in somewhat so that I have
plants that look green rather than purple.<g>
> Fortunately, I didn't have the need to do any retro-fitting. Th
> bought is a single, self-contained unit, including (I assume) th
> ballasts. The hood that came with the tank had two 24" fixtures
> two 15w Tritons. However, I didn't figure 30w of lighting was g
> enough over a 55 <g>. So all I did was remove the two 24" fixtu
> replaced them with the new fixture, which stretches the entire l
> tank. Now if I can just find another one like it I'll really be
> far as adequate lighting goes...
IMO, 2 4ft bulbs over a 55G tank is the bare minimum. I use 4
over mine.
> I'm in the process of checking out the more commercial lighting
> Atlanta. I'm also actively searching the net for web pages of f
> lighting places. You've got me convinced I made a pretty good p
> though...
Using the model numbers I gave you, you should be able to track
down the right bulbs. Your plants will thank you and so will your
wallet!
------------------------------
> From: Charley Bay <charleyb at hpgrla_gr.hp.com>
> Date: Thu, 21 Sep 95 9:26:02 MDT
> Subject: Re: Allelochemicals, Echinodorus
> > I think we are not all imagining the same thing when we use th
> > terms "light", moderate" and "heavy" planting.
>
> I think you are right--terminology is a big issue to me, and I
> don't know that everyone on this list has uniform understanding
> of these categories (I know I don't) :^>. I keep dropping back
> to my metrics in forest mensuration (because I know what that is
> and I'm really trying hard not to use terms like "co-dominant"
> and "intermediate", but I keep thinking some scale or "rules of
> thumb" would allow more consistent relation of experience.
You are right that some more specific terms would help. I suspect
as this part of the hobby matures, we will see more consistency of
terms. I think the meeting of the minds we have in this group
will go a long way in that direction.
> For my tanks, (the frugal, penny-pinching tightwad that I am),
> get enough plants so that each competes closely with another pla
> on at least two out of four sides. Thus, all of my plants have
> an "out" where they can grow into a space relatively free from
> competition, or can compete directly with their immediate neighb
> As in my previous post, I think this competition is important.
> do not have problems with "deformed" vegetation from lopsided
> competition, but can simply uproot those plants that may have
> problems and turn them around. Of course, larger plants don't g
> lopsided from competition with neigbors, so I don't need to upro
> them. :^>
>
> After some period of growth, the plants eventually "fill in" tho
> open spaces, and I may end up with 3 out of 4 sides or 4 out of
> 4 sides with competition (various levels of competition). Then
> I know I must prune.
I like that approach. It approximates what I have done without
really thinking about it.
> My schedule is rather hectic at present,
> and I must admit that I do prune back heavily, to a very minima
> amount of competition. I do not have significant problems with
> algae, (that may partially due to low light, 1-2 watts/gallon),
> but I am getting "good" growth (real quantifiable, huh?). :^>
I don't think I'd be satisfied with the growth I got with
1-2W/G.<g>
> > Certainly, a tank
> > can get so crowded that the growth rate drops off. I would no
> > term that "densely planted", I'd term it "over crowded".<g>
>
> Agree again. Of course, the rate is dropping off (with increasi
> severity) as competition is introduced. While some plants do gr
> better in the presence of other plants of the same or different
> species (usually a result of micro-climate modification),
In my experience this is especially true with Crypts. A single
plant of many Cryt species will just sort of limp along, while if
you have a big stand of them they are very vigorous
> I'm convinced that many of my plants that
> have heavy competition on 4 out of 4 sides have an NPP of zero,
> seem to exist fine for a while until I get around to pruning
> everything back (this is more easily demonstrated for rosette-ty
> plants than for stem plants that merely extend upwards.).
I sometoimes use this to advantage to "hold" a specimen that I
want to play with later, but don't really have room for right now.
I kept a baby 'Rubin' Sword under 6" tall for over a year by
putting it in a crowded location. When I had a good home
available for it and moved it, it quickly became a 30" plant.
> One more thought on competition: for many terrestrial systems,
> actual competition is almost *entirely* below soil. Many field
> don't have trees simply because the competition for root space i
> so complete that nothing can get a foothold (even though the
> established plant species does not appear to exude allelochemica
> In these fields, trees simply cannot grow because root competiti
> is so severe, even though sufficient light and water may be
> available. I am absolutely convinced that this also takes place
> in aquaria around mature species with strongly developed root
> systems.
I was thinking about this when reading the earlier part of your
post. I have another 'Rubin' Sword that is enormous, even though
it is crowded into one corner of my tank. BUT it is in its own
pot, with its own soil enriched substrate, and when it looks
lethargic, I repot it. So even though it's in a tight area, it
really isn't competing with other plants in the substrate.
> (I was over at George's house, and he told be to stick
> my finger into his substrate at one spot; I couldn't; the root
> mass was so well-developed, it was like trying to stick your
> finger through plywood).
Anubias and Crypts are particularly notorious for this. I am
planning to take down my 70G tank soon (and install cables at the
same time<g>) for exactly this reason. I can't even get my
fingers into the substrate to divide the plants any more. IMO,
_this_ tank _is_ overcrowded. And it is showing in decreasing
growth above the substrate.
> > George and I have what I would consider "densely planted" tank
> > and I know from what I've seen of his tanks and what I've read
> > from him that both of us aim for optimum growth.
>
> I am very impressed with George's tanks. His growth is excellen
> (Sorry, I haven't seen yours! :^> ) However, I know "optimum
> must be somewhat arbitrary. The farmer must decide if he wants
> the biggest ears of corn (space those plants far apart), or the
> most possible corn (pack them in there, more plants "more-than-
> compensate" for the decreased productivity of individual plants)
>
> That, I suppose, is the art; are we gardener (the population) o
> horticulturist (the individual)? Some of both, I should think.
That's why I like the term "optimum" growth, rather than "fastest
growing" or "biggest" or "most productive". From my perspective,
it is the growth rate where plants look the most attractive in a
display tank, while growing _at least_ fast enough to be a
self-sustaining population. I don't like to buy the same species
more than once if I can avoid it!<g>
> > So maybe in your terms, my tanks are "moderately" planted, sin
> > do whack away at them with a machete fairly frequently.
>
> That has statistically proven to be the most efficient method (m
> productive in terms of given resources and resulting biomass) fo
> a total resource investment over a given period of time. I shou
> do that, but I don't (I will use time constraints as an excuse).
I think it helps to have a background in terrestrial plants, even
if on the back-yard-gardener basis to have a better idea what
we're trying to accomplish in a planted tank. Every gardener
knows that you make your perenials bushier, and produce more
plants if you pinch back often and divide regularly!
> Sorry for the long post.
Don't be sorry! I've thoughly enjoyed it!
------------------------------
> From: MADSEN at ELMSG_WES.ARMY.MIL
> Date: Thu, 21 Sep 95 10:31:33 CST
> Subject: RE: Aquatic Plants Digest V1 #24
>
> I am replying to the comment about rooted plants outcompeting a
> for nutrients. Scientifically, there is no good basis for this
> if you mean nutrients in the water. Research has shown that roo
> plants take most of their required nitrogen and phosphorus from
> sediment, not the water. Algae are much more efficient at takin
> nutrients from the water than rooted plants. However, the dense
> will keep the sediment nutrients from leaching into the water, w
> then in turn promotes algal growth.
I have no argument with what you are saying, but I think this
comment was in regards to the fact that if you _use_ primarily
root feeding plants, you can keep nutrient levels down in the
water without compromising the higher plants. Also, in George's
original post, I don't think he was refering _only_ to rooted
plants. As we know, there _are_ many aquatic plants that pull
their nutrition directly from the water. That's one of the things
that makes plants like Water Sprite and other floaters so useful!
Karen Randall
Aquatic Gardeners Assoc.
Boston, MA