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- To: <Aquatic-Plants at actwin_com>
- Subject: Re: PO4/deficiencies/modeling
- From: Thomas Barr <tcbiii at earthlink_net>
- Date: Mon, 03 Dec 2001 21:02:27 -0800
- In-Reply-To: <200112032048.fB3Km9612973 at actwin_com>
- User-Agent: Microsoft-Outlook-Express-Macintosh-Edition/5.02.2022
Subject: Re: PO4
>> I "care" about the plant's needs.
> which is really a difficult thing?
No, not that hard. If you got one good eye, your up to it:-)
>you must be an eye to every kind of
> deficiency!!! E.g. how can oyu know when there is a deficiency of trace
> elements other than iron? how can you measure it?
Well you can actually... but it's a rather difficult process for our
purposes. It would not gain you that much either. The solution is easier
than determining the cause. Many of the deficiencies are similar in nature.
Algae almost always pops up as a result of stunted(deficent) plant growth.
Consider what your asking. Measurement of all 17 essential nutrients in a
water filled column/inundated substrate. By only adding these nutrients and
rather than bulk replacement(via water change and adding a known amount of
nutrient to a known amount of volume of source water) your going to have a
much more difficult time testing for each nutrient(a lot and quite often) in
each area and adding them as they used up. Now also consider the difference
of type and and plant mass in each person's tank. Some plants eat moreNO3
than others. Some aquatics use silicon, most don't. GH/KH etc. It's
possible but too much work. There's better way. Try to figure out what
general range gives the optimal plant growth. Tweak a little here and there
to get your perfect balance nutrient wise. This "range" is known. Proving
that it is "the range" is another matter. Maintenance practices like water
changes can allow you to keep "the range" relatively close without going
nuts testing, dosing and worrying.
If it got down to that no one would be able to do this hobby.
Now you can pick which state variable(much like the model program you choose
to play with to explore which nutrient has an affect on 1)algae growth, 2)
plant growth, 3) fish/critter health. A key feature in exploring this idea
and model is being able to keep the other nutrients relatively stable while
manipulating the one nutrient of interest. This is where folks trip up. CO2
levels are too low/high/jump around when testing PO4/NO3 etc, NO3 down at 0
most of the week or chronically, little to almost no K+, GH/KH too low
(Discus issues as I call them) or not having enough traces.
In assessments of model development we make assumptions. Since the traces
are in fact *traces* we will assume that they are all one element instead of
7-9 etc. We will assume light to be constant(there is bulb drop off in
lighting intensity over time) and basically you go down the line trying to
keep the variables that are important to the system and keep the model as
simple as you can. If you try to include everything in the model in will
become a monster and not be of much use. It's balance between reality and
We often take theory and try to apply it to reality. This is a bit the
reverse idea. Take theory and modify it till we get good practical results
with "a model fit". In this manner we keep the model simple but
realistic(hopefully). There is room for argument in the assumptions area and
it becomes more of an art in the development of a good model.
While not having used these model prior to this year, I have gone down the
list systematically one at time to see what effect different levels have on
aquariums. Light->CO2(KH)->NO3/NH4->K+/GH->PO4->Traces. Other items that
help suppress algae include frequency and intensity of disturbances(Joe
Connell work is a good classic read, hey he's at the lab! Nice guy too.). We
do this with water changes, glass cleanings, filter cleanings, pruning off
algae covered leaves(much of which you cannot see), removal of dead/ non
productive plant mass etc, blackouts. Some of our disturbances cause
algae(allow the fast growth specialist to make an appearance) like removal
of a large sword plant pulling up the roots (these supplied the substrate
bacteria with large amounts of oxygen) and adding NH4 and PO4 in large
enough amounts to trigger algae.
Other aspects that you can consider is that YOU are the herbivore. You can
even measure the intensity of your herbivory effects(if your consistent, I'm
not). You could treat this as a prey/predator dynamic also.
Shrimps, snails, SAE's etc all can be considered predators on algae and
treated as such with a model dynamic. They can be accessed for their algae
removal intensity rather simply but we need to be specific about _which
algae_, age of the algae(fresh growth on a sample tile would be eaten first
before some old tough algae covered leaf) and other factors.
If you have a problem or suspect a problem, follow the flow of nutrients
down the list. Trust your own eyes and be patient. If it appears like the
plant's growth is slowing down, it may be really slowing down. Give it
sometime to be sure. Do a water change(this cleans the slate) and add the
needed nutrients back into your tank afterwards. At least for a few days you
will have good conditions by doing this. If you add PO4, NO3, Trace 2-3x a
week including this you will have mastered the nutrients pretty damn well.
The rest is pruning, adding herbivores, playing with math models and other
>> Whatever level they need to grow at their best. You might
>> need more than that. You may be adding more from fish food or from the tap
>> water's content. You need to find all the inputs of PO4 before adding it
>> blindly. A 20 L tank is tiny. Add speck(perhaps 10 fine grains) and see how
>> the tank reacts. 2 watts a liter is very high light.
> ok! I made some test:
> PO4 (as ortho) =0.00ppm
> Fe (after adding ferric citrate this morning) = 0.1ppm ; tonight after 10
> hours of lights Fe = 0.04ppm
> NO3 (after adding NaNO3 this morning) = 5.0ppm ; tonight after 10 hours of
> lights NO3 = 1.5ppm
> GH=~ 3d
> KH=~ 3d
> CO2 = 20ppm
> consider that I have no fishes or shrimp.
> I think I can go for 0.5ppm of PO4 tonight, and measure tomorrow morning
> before that lights go on.
> Plants: Macranda is suffering for sure, its top leaves are not orange red
> as usual but very deep purple. Losing the old leaves.
> Glossostigma is leaving old leaves (on which greeen/brown thread algae -
> mono filamentous - is slowly growing), and many of the new buds are verry
> pale, some are are completely white with brown spot zones (dead I guess!).
> Eleocharis is growing very fast with apparently no problem.
> thanks for now!