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Algae and water movement

From:	NAME: DIONIGI MALADORNO
	FUNC: PRCI
	TEL: 201-812-3495 <MALADORD@A1@RNISD0>
To:	"Aquatic-Plants at ActWin_com"@INET@MRGATE@RNISD0

Here is my experience on this subject: in my 180gal tank (temperature 82 
degrees Farenheit,5 GH, pH 6.4-6.8, four 3' tubes with Icecap VHO ballast,
CO2 fertilization, medium fish load, mostly swords and crinum) I noted an
increase in blue-green algae when I decreased water movement turning off
one of the filters (a Superking, but I kept on a sponge filter with 
powerhead and a large canister filter). I had (and in part still have) high 
phosphates , I guess due to the use of phosphate-rich peat. Nitrates are
<10.
(By the way, is anyone else of the opinion that peat may increase
phosphates?).
This experience confirms the theory mentioned on Aquatic Plants Digest V1
#269,
but I would also add another possible mechanism, which is that water
movement
reduces in certain areas of the tank the amount of silt and other debris
which,
I guess suffocating the leaves, promotes the growth of algae.
I do whitewater kayaking, and I observed that especially at summer low water
movement and higher nutrients levels due to low river levels, associated
with high temperatures, induces the growth of algae in sections of rivers 
that were cleaner earlier on in the season.

Concerning hair algae, I have a different experience.
Before I stopped to use peat I had higher phosphates levels, and big green
hair algae used to grow only on the leaves of a sword just in front of the
powerhead. When I started to control phosphates, they did not grow anymore.
Same thing in a smaller tank I also have. In my tanks hair algae therefore
grow preferentially where water movement is higher. 


Dionigi Maladorno