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Re:Algae control?

Sorry, you hit my funny bone and this one's a bit too ripe.
 
> To effectively control algae, you need to remove an essential nutrient
> from the water column.

Remove CO2 then:-)
Out of all the "nutrients" it is required in the largest proportions
relative to the other. So why not limit the No#1 nutrient?
So will removing the CO2 cure algae?

This is why CO2 is often the culprit when dealing with algae. Many just
don't realize it or don't see it at first. Nutrients(NPK) run a second
place(often a lack), then the micro/ other macro nutrients last. There's
common sense stuff like water changes, maintenance etc but the above is
pretty much "The run down" every single time.
Removal is far more difficult if you use something **other** than plants.
It's very easy to add more CO2, very hard to remove PO4/GH/KH chemically not
mention a fair amount more expensive especially in the long term (For
example: Yope! I forgot to this week!)

 Things have their limits but in almost all cases a solution is there within
reach using this method of plants doing the removal work. They are good at
it. 
 
>Some people advocate iron, some suggest phosphate,
> other people swear by nitrogen. Personally, I favor phosphate because iron
> is a micronutrient and is required in very small amounts, and nitrogen can
> be fixed by blue-green algae.

Your wrong about the BGA fixing N2.

Oscillatoria, which is the only genera I've ever seen in all of the algae
samples from tanks, does not and cannot fix nitrogen from air/dissolved N2.
Other genera can..... but not this one. **All** Cyano's do not have the
ability to utilize N2 gas. This one does not possess heterocyst which are
obvious structures under a microscope and are required for the anaerobic
enzymes needed to break the N2 dimer. Therefore if it doesn't have these,
you don't get any fixing of N2. The genera Oscillatoria is heterocyst
lacking.....
If you have some that can break the N2 dimer I'd like a sample please:-)

FWIW:
Every body likely has some BGA just waiting in their tanks. Never seen a
sample with out it yet.

Regarding iron, since it is a micro nutrient and needed in much smaller
proportion and far less frequently(up to 3 weeks if using just an iron water
column source) it would seem to indicate that it should be the one to limit
things, rather than P that is much more critical for growth. Iron can be
added to the substrate effectively as well again keeping it away from algae
till the plants get growing well.

P usage can be quite high in a well lit/CO2 enriched tank. My tanks "eat" at
least 0.2ppm a day. Some tanks that are hungry will eat this much in just a
few hours. You can see a difference in plant growth. If she did a water
change say 50% adding fresh PO4(at 1ppm from the tap), it would be gone in
about 2 1/2 days assuming no other sources and no P to start with. Double it
and we get 5 days to zero.
So doing a weekly water change will give a nice P level with this rich P
water. Plants are fine with a little less or "pulses" but I like more PO4
personally. You need more CO2 to do this, but the other nutrients in the
tank are in good supply so this should certainly happen if the test(NO3, Fe
etc) are indeed correct.

> At any rate, your analysis indicates high
> levels of all three... 1-2 PPM phosphate is huge for instance, and will
> continue to cause you problems no matter how much carbon dioxide you add
> to your tank.

My P is that high and has been for many years. Oh ...and I got problems:-)
My tap has no P now but in the recent past it had 1.2ppm or so. I'd do a
water change and my plants always grew like mad for a few days afterward. I
have to add PO4 these days. Did some test to see how the plants would do at
low PO4 levels and was not happy both with algae and plant growth. Certain
plant species do poorly at low PO4 levels also. I added PO4 to my old high
levels and back came the great growth. I did this systematically in one tank
slowly raising it up and then all 4 tanks. My CO2, lighting, Trace, NO3, and
K levels where kept the same.

Why would someone have high nutrients across the board? Could it be that the
plants are not using it? Why would that be? CO2.
More light would help perhaps but if there's even 1.5 watts per gallon on a
tank the NPK should go down some over the course of a week. 80 watts on a 29
gallon is plenty to see a drop.

 A NO3 of 10ppm is not bad nor "high". I run mine lower these days but I did
run mine at that or a little higher for some time with higher fish
loads/less lighting etc.

CO2 is the big issue. Folks will find that the plants are flexible if this
part is dealt with in an effective manner. RO/DI/Resins/No surface movements
etc etc are not needed and are a hassle. Folks whine and cry about how much
a decent gas tank CO2 set up cost yet folks will go to all sorts of nutty
ideas(RO/DI/Add Acid to their tap water, have endless bouts with algae, fret
and spend enormous amounts of time dealing with an issue that is very simple
and easy to solve) to dodge the real issue. Folks not having good CO2 levels
is the cause of many myths floating around.

A commonality regarding CO2 often seen is folks with pH levels too high (not
enough CO2) because their "fish will be gasping at the surface" is often due
to inadequate circulation, poor CO2- (mixing,flows-irregluar) gas input.
High levels of nutrients not dropping also. Add that with GW appearances(see
Roger's post, which mirrors much of my experiences) which I have played
extensively with and it really points to CO2 issues......

As usual:)

Regards, 
TomBarr