|Hello. I am currently working on my sophomore
science project and am trying to think of a
topic. An idea I had was : How quickly does
algae accumulates on different surfaces, like
wood or plastic in various locations underwater.
(Deep, shallow, rocky, sandy, still, etc.) Is
that a good idea and would I be able to grow them
in small tanks? How would I go about doing that?
Thanks, Kim Young
|Question Date: 2004-02-28|
I can see a great deal of difficulties with it,
among them problems of:
-Contamination of different types of algae.
-Different nutrient supplies in the water you are
growing algae on.
-Actual measurement of the extent of algae
-Statistical issues (you would need to
conduct the experiment many times in order to get
a meaningful result).
-Controlling for other factors (e.g. type of
I guess that it depends on what your aim is.
If you are trying to demonstrate that algae
accumulates at different rates on different
surfaces, then it's a good project.
If, however, you want to
know which one accumulates fastest and which
accumulates the slowest,then you will have to be
VERY careful about your procedure.
suggest filling up your tanks with tap water,and
cleaning (thoroughly!) the surfaces that you want
the algae to grow on before adding them to the
tanks. You need to fill the tanks up at the same
time (tap water might have different amounts of
stuff in it at different times). You also need to
store your tanks all in the same place, with the
same light, etc.
For the algae, I would go to
a local pond or drain and take a sample, and
measure out a volume of water from your sample
(say, a tablespoon, or the like), and pour an
equal volume into each tank. Then you wait for a
period of time for your algae to grow and see
That sounds like a great idea. There are many
types of algae, but the way to find the one that
grows best in tanks is probably to talk to people
at a local fish store and see what tends to build
up in their tanks or their customers' tanks.
You might also ask around your school to see
who has a tank that needs cleaning. The owner
will probably be happy to donate their algae to
If you requested people's used jars or
2L bottles, you will probably have plenty to use
as tanks. You will also have to make sure you use
the right kind of water. Tap water will probably
have too much chlorine. You can ask the people at
the fish store, or your friends with fish, what
they use to treat their water.
Think about what
things must be identical in each tank and which
things you want to change. Remember that if you
change two things at once, you won't know which
thing had an effect on the algae. I would
advise wearing plastic or latex gloves to protect
yourself from contaminants. Also, wash your hands
and equipment well.
However, you need to think
carefully about how you want to quantify the
AMOUNT of algae growth on these different
If you put in a piece of plastic and
measure the mass of it before and afterwards, that
might work if you have a very sensitive balance
(say it can measure to 0.01g or so). Measuring
sand would be more difficult! You might want
to change your project slightly to look at
differences in algae growth in, say
light levels (high/low), and/or
temperatures (warmer/colder), and/or
nutrient levels (if you have a way to add
nutrients to water).
Generally, algae growth
should be faster in higher light, warmer water,
and water that has more nutrients.
That sounds like a great idea for a project, and
you can definitely do this in aquarium tanks.
Testing growth rates on various materials
shouldn't be a problem; testing the effect of
depth will be a little trickier in tanks. Perhaps
you can get at the depth question via a more
indirect route light intensity. As you go deeper
in the water, the light intensity will decrease.
Thus, you could set up multiple tanks with
different light exposure and compare growth rates
on the same materials under those different
Id recommend setting up the tanks
away from a window or other uncontrollable light
sources so that you can regulate the amount of
light they get. And try to keep all your different
pieces of material at the same distance from the
light source. It would be ideal if you could use
tanks with the long fluorescent bulbs in the lids.
That way the light is shining down equally to all
areas of the tanks. Then you could modify the lids
to block some of the light coming down, or buy
lower watt bulbs to create dimmer conditions in
the tanks with less light.
You should probably
get several blocks of each material youll be
using. First of all, you need to have enough
pieces to put copies of every material in each of
your different light treatments. But secondly, you
might also want to consider putting two or three
pieces of the same material in each tank, placing
them in different areas (corners, edges, middle).
This should help control for any variation in
growth that might occur in different locations,
because it may be the case that certain areas of
the tanks will grow algae faster than
Now the big question: where do you get
Believe it or not, the easiest way
to deal with this is by going to your local
aquarium shop or a pet store that sells fish. Talk
to the employees there. They deal with algae in
their fish tanks all the time (although to them
its a hassle!) so theyll have a lot of anecdotal
information about the stuff. And theyd probably be
happy to supply you with a source of algae for
Anything should work, but
ideally a floating plant that you could rest at
the surface of your tanks would be best. That way
its far away from your blocks of material. An
algae-covered rock would work too, but then youd
have to put it on the bottom with your materials,
and youd have the problem of the rock being closer
to some of the blocks than others. And take into
consideration what type of water youre using - if
youre doing the project in freshwater tanks, ask
for a freshwater algae sample.
When you get the
algae into your tanks, youll want to help
stimulate it to grow. The algae will do it on its
own, but a way to encourage it is by leaving the
tank in the dark for 18-24 hours on the first day.
The dark will stress the algae a little bit. Then
when you turn the light on, the algae will be
quick to take advantage of the good light
conditions to reproduce. After the first day, you
can then begin to simulate "normal" day/night
light conditions. Try to turn off the light for 8
hours every night. Pretty soon you should have
algae growing in your tanks and you can start
comparing the growth rate and abundance on your
Good luck with your project!!
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