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Discussion Starter · #1 ·
My daughter is looking for ideas for a 5th grade science fair project. We saw the thread posted last September looking for 7th grade science fair ideas.

My daughter thinks that many of those might be too difficult and is wondering if anyone has any easier (or different) ideas.

Last year, she did an experiment growing brine shrimp eggs in glasses with water solutions containing various concentrations of salt.

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Ideas posted in the previously mentioned thread included:

  1. Comparison of tanks (with or without CO2):
    a) tap water & pea gravel
    b) tap water & enriched substrate
    c) water column dosing
    e) both (?)
  2. Algae growth in a tank with established algea growth, after 30% water change, above and below the water line, when water was changed.
  3. Plant growth in two tanks, with any of the following variables:
    a) DIY CO2 in one and not the other
    b) actinic bulb and the other with a 6700K bulb
    c) fertilize only with substrate tabs in one,
    and only water fertilizing in the other
  4. Get a 10g tank. split it down the middle with some kind of dark porous divider. Get two clip on light fixtures. On one side aim it down with a regular light bulb. The other side aim it down with a daylight spiral bulb. Record the plant growth and note the effects on light spectrum on the plants.
  5. My 7th grade science fair project was a study on the effects of phosphorous from dishwashing liquid on algael growth in a marine environment. Im sure you could do freshwater instead. Basically, I added different concentrations of different soaps, to different contained systems, each with an algae-covered rock, and I studied growth for two months. If you can get your hands on a phosphate test kit, and also nitrate/nitrite, etc, you can see exactly what the differences are between different products and at different concetrations.
  6. DIY CO2 as a great visual science project. If you use a Hagen ladder the CO2 bubbles can be watched as they get smaller going up the ladder dissolving into solution. Focus on the relationship/effect CO2 has on things like pH, KH and photosynthesis. Even the yeast can provide for an informative discussion about the Kreb's cycle and respiration. If you would like to add a more effective way to disburse the CO2 here is a reactor/filter; Yea, it's ugly. A DJ100 has a clear view of the bubbles when they enter the filter so a bubble counter is not needed and you will get a quick change in pH with only yeast culture.
  7. Nutrients are involved with photosynthesis and respiration so some simple charts would show the relationship. You could also show something on Liebig's Law, (Law of the Minimums) to explain the limiting effects on plant growth when a specific nutrient is absent.
    http://en.wikipedia.org/wiki/Photosynthesis
    http://en.wikipedia.org/wiki/Citric_acid_cycle
    http://www.avocadosource.com/tools/F...iebigs_law.htm
    All this can be done using algae (Cladophora), larger plants, fish (fresh, brackish and marine environments).
  8. An excel vs no excel as Hoppy suggested would be great. Especially if you put several species of plants in the tank
  9. The following:
    1. Tank full of tap water
    2. Measure and chart for all possible parameters (like amonia) as you would a new aquarium.
    3. Perhaps note how much of chemicals present would, um, kill a fish...
    4. Add hornwort or some other fast-acting plant.
    5. Measure and chart parameters daily until tank reaches point where one can consider adding fish.
    6. Different tanks with different kinds of plants could be compared. One tank could even have media from an established tank.
    7. End result: happy fish (or maybe snails, shrimp) in a little world you have made them
  10. Using the same type of plant (preferably a fast growing plant like Eleocharis or a Hygro), in one tank just put the plant with regular substrate and leave it there with just ambient light. ---- In another tank do the whole DIY co2, fertz and light, and record the difference in growth between the two tanks over a period of time. If you can spare more tanks or containers, then you could spread it, one with nothing, one with only light, one with only co2, one with the full monty.

:flick:
 

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Snail herbivory might be kind of interesting too. You could have a tank with a barrier impermeable to snails down the middle and with snails on one side but absent form the other side. Of course, the snails would evnetually get across the barrier but you could see some interesting effects in a few weeks.
 

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Three weeks?
The only thing in any of the posts above, that you could accomplish in three weeks, is the amount of algae in two different "identical" tanks using vastly different light sources.

Or the amount of algae growing in two different tanks under the same light but with vastly different water conditions. A blackwater tank and a freshwater tank for instance. Put the tanks long side by long side and use a 24" strip light.

Good luck.
 

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At the California State Fair every year the 4H kids bring in sows to give birth to their babies during the fair. People get to watch the whole process for the two weeks of the fair. I have found that my grandchildren always love to see that part of the fair. And, that suggests to me that a simple experiment with a couple of guppy females and a male one, in a 10 gallon tank, with a few plants, to show the difference would be a hit. The females should deliver at least 10 babies apiece, so the demonstration would show how live bearing fish do their thing.
 

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Discussion Starter · #10 ·
From Elena (5th Grader)
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I was thinking about something like 'do fish effect the groth of plants' what we think we will do is have two 5 gallon aquarium's put plants in both. and add fish (small guppies) into one. we need to know if you guys think that would work (remember: 3 weeks) if so what plant would grow the fastest?
 

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That would work if you get a shop light and mount it above the two end to end tanks, so both tanks get the same light, and keep that light on 8 hours a day. Add the same amount of pool filter sand to each tank. Plant both with equal numbers of plants, and equal sized plants. Vals might work, or stem plants like Ludwigia repens, or a mix of the two. Keep the tanks set up in a heated room with the temperature controlled to at least 70F. Add about 10 guppies to one tank and none to the other. Feed the guppies every other day, or 3 days a week, and only as much as they eat in one minute, dropping one flake at a time while doing that. (Otherwise the excess food would also act as a fertilizer for the plants.) In 3 weeks my bet is the the one with fish has twice the growth as the one without.
 

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It might be interesting to compare emersed vs submersed growth rates of the same plant. Or perhaps just documenting the transition from emersed form (buy some four-leaf clover that usually comes emersed and put it under water and watch all the old leaves die and new ones with a different shape grow out).
 

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From Elena (5th Grader)
---------------------------

I was thinking about something like 'do fish effect the groth of plants' what we think we will do is have two 5 gallon aquarium's put plants in both. and add fish (small guppies) into one. we need to know if you guys think that would work (remember: 3 weeks) if so what plant would grow the fastest?
That would work if you get a shop light and mount it above the two end to end tanks, so both tanks get the same light, and keep that light on 8 hours a day. Add the same amount of pool filter sand to each tank. Plant both with equal numbers of plants, and equal sized plants. Vals might work, or stem plants like Ludwigia repens, or a mix of the two. Keep the tanks set up in a heated room with the temperature controlled to at least 70F. Add about 10 guppies to one tank and none to the other. Feed the guppies every other day, or 3 days a week, and only as much as they eat in one minute, dropping one flake at a time while doing that. (Otherwise the excess food would also act as a fertilizer for the plants.) In 3 weeks my bet is the the one with fish has twice the growth as the one without.
I think this could definitely work! Like Hoppy said, you just have to make sure they have as close to the exact same parameters as you can get, for example 1 long light that spans the 2 tanks, the same filter on each tank, etc. Sunset hygro, hygro difformis (water wisteria) and "foxtail" are all good fast growers, or even a floating plant could work, just put like 5 pieces of duck weed or red root floater / pistia in each tank and see what happens.
 

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I think thats a good idea. One really good thing to do would be to weigh the plants before you put them in, to make sure you get as close to the same plant weight starting off, and you could weigh the plants at the end of the 3 weeks to give you some good quantitative data.
 

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I think thats a good idea. One really good thing to do would be to weigh the plants before you put them in, to make sure you get as close to the same plant weight starting off, and you could weigh the plants at the end of the 3 weeks to give you some good quantitative data.
Just remember that aquatic plants are mostly water, so you are weighing water if you don't first dry out the plants. But, if you do dry them, they weigh almost nothing, so it takes a good gram scale to measure the weight.
 

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Just remember that aquatic plants are mostly water, so you are weighing water if you don't first dry out the plants. But, if you do dry them, they weigh almost nothing, so it takes a good gram scale to measure the weight.
Not only would it take a good scale, but the plants won't recover from being completely dried out (i don't think) so there would be no good way to do the "before" measurement really, unfortunately. And since there's also no really a good way to account for the water, weighing may not be the best method unfortunately.

I think making sure the plants are the same height (this you could measure) and of similar diameter (you could probably also measure this) to start will give you a good way to measure growth quantitatively though.

If you use a stem plant or a grass plant she could conceivably count how many sets of leaves there are, or how many blades. By "sets of leaves" I mean if you look at a lush stem plant it will have leaves growing in a ring around the stem every 1cm maybe, but a plant not growing as well that gets "leggy" might only have leaves growing out of the stem ever 3cm or so....does that make sense? i hope so! :hihi:
 

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Discussion Starter · #17 ·
This time its Twimbo:

Elena has been very happy about all the feedback and advice. She had to go to bed, so I'm posting tonight. She has read every word that you folks have posted. She calls you "my nerdy friends." (What does that make me??) I don't think I was supposed to post that. :icon_cool

Here are some of the plants that we already have and we think might work:

  • Hornwort
  • Rotala Rotundifolia
  • Sunset Hygro
  • Rotala sp. nanjenshan
  • Red Root Floater
  • Duckweed
She plans on setting up two 5.5 gallon tanks and spanning the two tanks with a single T5 25w bulb (36"). She will put the same number and length/height of stems in each tanks, but in one tank she will add about 7-8 juvenile guppies.

Despite the concerns that we're raised. I think that I'm going to suggest that she both weigh (WET) and measure the lengths of all plants before and after experiment. I have two old HOB filters that are pretty much the same, she can put one on each tank.

She plans on feeding the guppies daily (most days). Thanks to Hoppy for the advice about feeding them slow to make sure that the fish eat everything. I think that is a good touch to the experiment.

Questions:
------------

1) Is the single 25w light enough for two 5.5g tanks? Would a stronger light help or hurt in this experiment? I could use my 2x38w T5-VHO fixture and hang it a bit higher over tank. Seems like overkill to me. Then my 38g tank would have to survive with low lights for 3 weeks.

2) Any reason not to use a extra bag of Eco-Complete in this experiment? Would it help the plants in both tanks enough to minimize the effect of the fish? Would pool sand be better, in that it would have less to offer the plants and better highlight the different between the two tanks?

I think I'm going to set her up with her own account here on the PT site, so that she can keep a journal of her project for others to watch and comment on.

She hopes to set this all up tomorrow evening. Any final comments or suggestions would be appreciated.

Thanks
 

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I think that sounds perfect! It will be interesting to see if some plants do better in one tank over the other but some show no difference.

to answer your question, I think 25w t5 will be more than enough for this experiment, any more and i think you'll end up with algae .

Also, I think using an inert substrate like pool filter sand will definitely illustrate the difference between the two tanks better than if you use eco complete. It eliminates another variable (i'm a scientist, i'm all about reducing the number of variables :hihi: :proud:)
 

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I agree with Karackle about both the lighting and the substrate. Also, I would limit the plants to only two species, both of which have to be easy to grow plants. So, I suggest the Sunset Hygro and the Red Root Floater (duckweed might be better, but I think it would grow too much.) This shows the effect on plants that can get some nutrients from the substrate and plants that depend on the water alone for nutrients. Any more plant types than that will likely make it too confusing. I noticed that Tom Barr seems to do his testing with no more than a couple of species at a time, and if anyone knows how to do that he does.
 
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