Principal causes of

BGA are 1) dumb luck and 2) excess nitrates.

Excess NO3?In terms of what?

You're preaching to the choir, perhaps reply to the post
that made the claim. Everyone ends up inoculated with BGA,
and BGA doesn't care about NO3 - it will fix it's own nitrogen.


Wrong, I've looked at many samples from all over the world, each one
except for one, had the same genus, Oscillitoria. The other was
Phormidium.

This genus(Oscillitoria) does not have any nitrogen fixing species
except for some with __hetrocyst__ which are clearly distingushable in
a microscope.
I've never seen any heterocyst yet. No heterocyst, no N2 fixing going
on.
It's that simple for this genus.

Some Azolla had some Anabena etc, but that's the only one I've ever
found in an aquarium.
I am a researcher at UF, I study Phycology, algal taxonomy is what I
do.
Several other Germans also report the same regarding aquarium BGA.

BGA has plenty of NO3, NH4 available in a tank if you have fish waste,
some plant decay etc, you have plenty iof Nitrogen for this species.

What you do NOT have is enough NO3 for the plants.


BGA and most other algae appear when something runs out, rather than
somethuing becoming excessive.

Eh? Life is a constructive process. It frankly doesn't care
if, or when, "something runs out" if it has no biological
use for that particular "something". Thus, BGA, or anything
else, simply cannot grow for LACK of a required component.

When something runs out relative to plants. BGA need next to nothing
to do quite well wereas the plants need far more.

PO4 causes BGA?

Ok, "Cause" was too strong. Technically, BGA "causes" BGA.
P only helps it along, and research suggests P is one of
the inputs through which it can be limited.

You'll limit your plants as well and I have a lot of PO4 in my tank
yet have no BGA or any other algae for that matter.
The range required to do any limitation of BGA by PO4 limitation is
less than 0.003ppm, that's beyond any test kit you own unless you have
a very good research water testing lab. If you have fish, plants in
there, there's enough PO4.

Adding more PO4 is not going to encourage algae if there's enough
plant biomass that's growing, it's going to encourage plant, not algae
growth.
So when something runs out, lack of something, this harms the plants,
not the algae.


NO3 is surely not limiting for BGA. But anything that the
higher plants can store can likely be used as a limiter.

Such as?
You pick the nutrient and the plants will always have a higher
requirement than the BGA for both growth and maintenance with FW
algae.

Some of the traces, perhaps. Run an iron poor tank, spike
once in a while, just near the point your higher plants show
chlorosis.

You are not going to limit iron either, plants leech out more than
enough(especially and densely packed tank full of plants) for BGA,
Green water and most other very small algae.

P is a good choice because it is a macro. Plants and algae
need "lots" of it, relatively speaking. Thus it might be
considered easier to limit.

How does limiting the nutrients prevent algae and still grow plants
well?
Plants need much more of everything than algae.

The biomass is mainly plants, harming their supply effects them and
slows their growth down.

That's simply wrong.

Really? You have science to share?

Search the web for PMDD, or "Poor Mans Dupla Drops". Not so
much for the formula, but it's development came from quite a
bit of interesting research regarding algae.


But the assumption made about excesses causing algae is wrong.

Well, let's define excess. Greater than 0. Phosphate is a
required component for life. If you have 0, you have NO
life, none, not at all. BGA, or otherwise.

Sears-Conlin seems to have gone to quite some length to be
so flatly declared "wrong", without, at least, a couple of
dozen pages refuting them in a bit more scientific way.

A couple?
How about everyone at IFAS(Center for Aquatic Weed Research at UF),
see Bachmann, Hoyer,
Canfield et al Hydrobiologia 470, 283-291 2002.
"Relations between trophic state indictors and plant biomass in
Florida lakes".

They looked at 319 lakes from very oligotrophic to hypereutropic
lakes.
Most were shallow(like our tanks), fairly warm water systems full of
plants.
They found no simple relationship between trophic state(Total PO4 for
example) and macrophytes.

You can add PO4 directly to a planted lake with 50% or more PAC/PVI
and still have gin clear water and only enhnace the plant growth.

This is not anything new.
SeaChem now sells PO4 supplements due in large part to me.

I did a number of my own experiments also, far more rigorus and longer
term than anything Paul or Kevin have done anmd talked about.
I've been dosing PO4 for about 12 years now, 8 years knowingly.
I've measured daily uptake rates in my tanks, even using non iron
substrates etc to prevent preciptation with FePO4. I've done this many
times over the years.

Additionally one of my study sites has water coming right out next to
an old Phosphate mine. It's got hard water, lots of PO4 and loads of
plants all the way down for over 6 miles. Ichtucknee springs. Not a
bad office

You are wrong.
Many/most species of algae can store PO4 for up to 100 generations and
survive at far below limiting conditions for plants.

Again, you have any science to share?

Yes, I do. I'll dig this one out, I'll post it or send it to you if
you want.

Look, Algae is a one
cell plant.

No, algae are not all one celled, there are hundreds of seaweeds and
filamentous, colonial species that are macroscopic, hence the word use
of "macrophyte". Chara and Nitella for exmaple look very much like
plants.

It grows by fission and spore. How can a spore
possibly collect P from it's parents? "

I suggest you look up Diatom reproduction, then consider the storage
of ployphosphates in diatoms, cyanobacteria, various green algae etc.
Zoospores can be close to the same size as the parent cell. The size
of the spore does not tell you how much PO4 it contains inside at all.
Generally the spore is very rich in nutrients, much like a seed.

Being one celled, and
without a nutrient transfer system, how does P magically
migrate to subsequent fission generations?

Algae does not need that much PO4 to begin with and see above.

The cell splits,
roughly 50% of the material is split between two new cells.

Both must now acquire materials to double their size. How
can the ultimate parent possibly, even remotely, "store"
enough PO4 for "100 generations"?

I'll defer you to the paper(I'll post it later)and suggest once again
to look at how diatoms reproduce and the size of spore does not tell
you if there's enough PO4 or not, the alga only needs a tiny amount.

If you maintain 0 Phosphate - algae can't get any.
Oh yes they can.

Really, when is 0 not 0. BGA can fix Nitrogen, when NO3 is
0. But, P? Unless the BGA can crawl out of the tank and
acquire some dirt for themselves, 0 defines "can't get any".

Because the PO4 level is so low your test kits cannot measure it.
Ulrich (1989) suggested that 0.003ppm of less of PO4 might become
limiting for many species if eukaryotic algae.
There's plenty of PO4 from fish waste, plant leeching/decay of lower
leaves, bacterial leeching, it's a whole other world when they are
this small.

Even if you tested none in the water column, they very well maybe
getting plenty from the plant's leaves through leeching and assimilate
the PO4 before it accumulates in the water.

When you test the water, you are testing nor taking into account the
PO4 in the plants and also the other algae.

So you only hurt plants growth, not limit algae growth through PO4
limiting approaches.

Fish food, and plant leeching is plenty for algae.
They might slow down some, but they will still grow fine, BGA is no
exception.

Then were are not talking 0. You have inputs.

That's the point, to have fish, grow plants etc. How does one have
plant tank problems without plants?:-)A few have no fish, but they
often have snails, etc.

If those
inputs are kept below total consumption demand, the inputs
are peaks and will return to zero.

During that non-0 time, algae, BGA and other, will surely
take advantage. So will the higher plants.

BGA has some effective doubling rate. If the P is available
for a short enough period of time, the BGA doesn't have much
time to double. Yes, it will expand, but 1 cell growing to
2, for adequately small random values of 1 and 2, does not
an outbreak make.

Well plants, and algae, can store a great deal of PO4 as luxury
consumption, they really don't need much, so size it not an issue.
An algae is only .05% PO4 by dryb weight. Not much.

Meanwhile, in a P deprived tank, there is little leeching
from the higher plants.

Are you sure about that?

They are in acquisition and storage
mode, hungry.

They are stressed, when things are stressed, they leak _more_ as a
rule.

They are slower than BGA, to be sure, be
we're back to the small random values of BGA doubling in a
competitive environment, returning P to 0.

Well then how ever do planted tanks grow without algae?
Plants need far more PO4 than algae.

You need to prove this to yourself, not me. I already know these
things.
Dose PO4, measure the uptake, see if the decline is due to the algae
or the plants.

It's that not hard to do this, adding more should cause algae correct?
That is what you are saying and it's simply not true.

I added KH2PO4 to a planted tank that had stable NO3, trace,light, CO2
levels and routine mainteance.

I added 1.8ppm of PO4 as tested by a Lamott and a Hach test kit. These
were checked againts known standards I made up.

This amount declined at the rate of 0.3ppm a day in an already richly
saturated PO4 tank(so that influences of luxury uptake are minimized
and binding with iron etc also played small roles).

If you remove the plants, you'd be lucky to see any decline over a
week

Don't take my owrd for it, try it yourself.
Ask folks with nice tanks say on DFW or SFBAAPS plant club list.

If the plant has what it needs to grow well, then it will do well and
the algae will not.

Algae is not a "plant"? Please share the biological
differences are you aware of between "plant" and "algae"
that would account for one "doing well", and the other not,
when adequately offering everything "plants" need?

Okay you want semantics and precise names, heck I teach Botany:-)
"Algae"= the embryo is not retained on the parent plant, the
reproductive structure is only singled celled.

"Plants" the embryo is retained on the parent plant, the reproductive
structure is multicellular.

That's the basic difference.
The term "embyrophyte" is sometimes used in cladistics.

There are a couple of exceptions, particularly with green spot algae,
Colechaete which does reatin the egg but it stilll has only single
celled reproductive structure. This genus and Chara are thought ot be
the ancestors of all land plants for some of these reasons.

It's like having a mouse and an Elephant and feeding both the same
amount and then deciding to feed less. Which will starve?

Yes, exactly. If you have a mice and an elephant in a
sealed room (tank), and you throw 100 peanuts a day (P) into
the room... The clearly hungry elephant snorts once and the
mice get none. Maybe the elephant's clumsiness leaves the
mouse population 1, or 2, or 10 peanuts. Not enough for
mice to breed as rapidly, or support a large mice population.

So what happens when the supply is too low for the elephant to survive
in good health? The mice are still fine.

Now, feed the room enough peanuts to meet everyone's demand.
They elephant is happy, and the mice breed. Many mice, so
many mice.


Well where are my mice then?
If what you claim to be true, where is my algae?
How come many folks, Paul Sears as well, add PO4 anmd note plant
growth/health increases and no algae blooms?

I had it(PO4) for decade, I loved it and so did my plants.

P has never done it for me, personally, in any form. Now,
my plants, I'm told, enjoy it immensely.

Well, don't knock it till you try it.

and good light. And, yea, use
Adding KNO3 regularly will generally cure BGA after you kill it off
first by doing a 3 day blackout, combined with 2 dosings after 50%
water changes right before and right after a blackout. Then regular
routine dosing of KNO3.

Why do you imagine KNO3 helps? KNO3 is 50-0-50 fertilizer.
May I call your attention to the complete lack of P.

May I call attention to Nitrogen limited plants? The BGA need far less
Nitrogen, healthy plants = poor algae growth.

Plants don't grow well when they don't have enough GH, CO2, NO3, PO4,
K+, and traces.

BGA fixes its own NO3,

Some spcies, not the blue green mat that engulfs folk's tanks, njor
the stuff that grows along the bottom along the gravel line, nor the
stuff that grows in the vegetative cones of plants.
They must have the heterocyst in order to grow.

so there is no point in limiting
that. All you'll do is deprive your higher plants. Deprive
the higher plants of NO3, and you lower their competition
for P, and everything else.

But PO4 is not limiting. If what you claim is true, then I should have
algae and so should 1000-s of other folks.

So, what is PMDD? Well, a N-0-K fert with micro (Ca, Mg,
which is not just GH, btw, you can have high GH as all Mg or
Ca, and none of the other - and dead plants will ensue) and
the trace elements. All needed in proportion.

Except enough traces(attempts at 0.1ppm residuals) in many CO2 tanks
with light over 2w/gal.
Do look at the lower CO2 levels(~15 vs what I suggest 20-30ppm), the
lower light by NO FL's bulbs(vs PC bulbs used these days) when you go
back and re read what Paul and Kevin said.

Your routine
use of KN03 is incomplete

Out of context, yes, but often it's mainly NO3 and perhaps K+ that are
slowing plant growth down, the orignal poster stated the conditions so
I did not focus on that aspect, they were already known and assumed to
be true.

I did say previously:

"I added KH2PO4 to a planted tank that had stable NO3, trace,light,
CO2 levels and routine mainteance."

- unless you are bringing in the
rest in with water changes. But, not everyone's input
waters are complete in this respect. Some use RO, some have
home softeners, some use strong micro-pore carbons to crack
chloramines (and lose metals in the process), some are just
lacking this, or that, in their tap.

You might want to read the plant club sites, read post on the APD
regarding this topic and simply ask around especially folks that win
contest with their tanks, many add PO4.

Hope this helps.

Regards,
Tom Barr