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Algae Sequestering of Nutrients (was Plant eating SAE's)

Subject: Plant eating SAE's? 
From: krandall at world_std.com

First a brief comment on the role of algae in freshwater aquariums:

>Our first line of defense is, or should be, our plants.  
>But there's nothing wrong with using algae as PART of the nutrient 
>sequestering process, and then allowing it to feed some of the animals 
>we wish to keep.

In nature, algae play a dominant role in nutrient sequestering. I suspect
this is also true in areas where vascular aquatic plants are also present.
In our planted freshwater aquaria, I hope that the algae represent such an
insignificant fraction of the biomass that their contribution to nutrient
sequestering would be extremely unimportant. 

 Now, on to the more interesting question:

>thing I've noticed is that a lot of the people who are advocating the use
>of bleaching to totally avoid the introduction of filamentous algae, also
>seem to have a fair amount of experience with green water. (they also
>mostly use soil substrates, it seems to me) They seem fairly nonchalant
>about it, and seem willing and able to cope with the occasional bloom.

OK, I fess up. I use soil in my tanks. (a small amount, perhaps equivalent
to the amount recommended for laterite). Occassionally, I get green water
in one of these tanks. But, I am not sure I put myself in the category of
bleaching to totally avoid the introduction of filamentous algae. I just
like to avoid two or three species. <g>  If I had a moderate level of
copper in my tanks, I would not be as concerned.

>is one of the REASONS they see more green water at least partially because
>they limit the number of other types of algae that are present within the

We know that many different types of algae do not seem to co-exist in
equally large numbers in the aquarium. Many species are undoubtedly present
simultaneously, but a few types seem to dominate at a particular time. I
suspect that has to do with preferential nutrient ratios and
allelochemicals. If the later is the reason, these same chemicals may be
affecting the higher plants. So, this is another reason that I do not want
to have any attached algae in my tanks - if I can help it. 

That is not to say that I never see any attached algae. I do occassionally
have to clean the front glass and see a speck or two on the leaves.<g>  In
the more quiet areas which do not get a lot of water circulation, a small
clump of filamentous algae can also be found. When I start to notice other
algae, however, it tells me that something is wrong in that tank. Because
when the plants are going gang busters and sending out their daily streams
of bubbles, the algae does not have a chance. I don't keep as big an
arsensal of algae eating animals anymore -- I only have a pair of farowella
and one SAE (its friend recently jumped out) :-(   
There is also nothing prettier than a tank full of algae free plants. They
seem to sparkle!

>_Something_ is likely to make use of any excess nutrients available in the

In my case, algae is only taking care of excess nutrients when I carelessly
or inadvertently introduce some phosphate laden soil particles into the
water column. This mostly happens when I uproot particular plants (the soil
doesn't necessarily start out with a lot of phosphates, but over time I
believe it soaks it up from stuff which precipitates out of the water. Same
with laterite, except that laterite's particles are larger and do not
appear to stay suspended as long). I would like to hear from others that
get green water to see if there is any connection to choice of substrate
materials. Any laterite users out there? <VBG> Also, it would be
interesting to hear from others who may be using undergravel heating to see
what kinds of algae if any they see.