Science Buddies: "Ask an Expert"

Hi! I am hoping you can help, because we really need it.

My 5th grade son wants to build an aquaponic garden for his science fair project. He has read that aquaponic gardens are very successful at growing leafing plants, but there are different schools of thought as to whether there are enough nutrients in the same exact system (with no nutrient supplementation) to grow a fruiting plant.

He wants to discover if the same aquaponic system that can grow a leafing plant can also grow a fruiting plant, and his prediction is that the system will have enough nutrients to do it.

He is setting up two systems exactly the same - same size, same number of fish, same grow bed medium, etc. The only difference is that in one he will plant lettuce seeds (to show a successful leafing plant growth), and in the other he will plant tomato seeds to discover if they will grow.

We thought the lettuce system would be the control - what we're testing against. But we're in the midst of a big discussion with our science teacher over whether or not the question my son wants to answer is technically a "scientific experiment" that can follow the scientific method and what the various controls and variables would be for this experiment.

I am at a loss because I'm getting so many different opinions from different people. He would prefer not to have to do a soil growth vs aquaponic growth experiment, but a few people have told us we have to do it for the control. If this question isn't right, what question could he ask that meets the scientific model using the two gardens we will have?

Do I sound confused? I am. I thought his question was pretty straightforward but it seems it's much more complicated and I need help to ensure I'm teaching him the right thing. Any suggestions on what we can do here to make sure his question leads to a successful experiment would be greatly appreciated.

Hi!

Excellent start, glad to hear of your son's interest in aquaponics.

Based on my personal experience, I'd say he choose one of the following options. If he'd like to simply compare the growth of leafing vs. fruiting plants in an aquaponics system, I agree it'd be a bit difficult to come up with a good control, but his variables are clear. The independent variable would be the type of plant selected, and the dependent variable would be the growth of the plant (measured in length, I assume, or any similar measurement). On the other hand, while I understand he may not want to do a comparison of soil vs. aquaponic growth, that would make it easier to select a clear control - the traditionally soil-grown plants.

Perhaps other Experts can chime in to provide a more balanced perspective.

Hope this helps! Please post back with more questions. (:

Thank you so much for your response scibuddyAK! I truly appreciate the information and understand what you're suggesting.

After talking to my son about how we can revise this experiment, and running it past his science teacher, we've decided to go at it from a different angle. He's going to test whether increasing the number of fish in one tank which will increase the amount of waste (nutrients), will result in a faster growing/larger yield than the tank with the standard number of fish.

We actually built the two systems yesterday and (other than having to get smaller tubing because the grow beds flooded too quickly), the systems actually work. We're going to let them cycle this week to get the water ready for the fish and will be adding the goldfish next weekend. My son is so excited - I truly hope we yield a "crop" because I know the sense of accomplishment will inspire him to stick with this project over the next several months.

Thank you again for your help!

Hello Gruvymomma,

I'm happy that you found this site useful in helping with your aquaponic experiment, although now it sounds a bit different, which is great also. Here are some resources that you may find helpful in organizing your son's project. This is an overview of the science fair process: https://www.sciencebuddies.org/science- ... ndex.shtml.

Also, I found this experiment through this website--is this the experiment your son will be using? If not, take a look at it anyway for some good background information as well as for a resource: https://www.sciencebuddies.org/science- ... p032.shtml. Here are related projects as well as information on professional careers in aquaculture: https://www.sciencebuddies.org/science- ... ojectideas

Please post again in this same thread if you have further questions or need any help at all. Good luck! Sounds like you are off to a great start!

Hi Gruvymomma,

No problem; always happy to help! I'm glad you've figured out the goal for your project!
Just as a side note, since you had inquired about a control earlier, I assume your control for this project would be a tank without any fish? I think that would be a logical angle to approach it from.

Please let me know if I can help in any other way.
ScibuddyAK

Sarahlaugtug - thank you so much for your post. Yes, we've been all over this site - it's wonderful! The experiment link you posted is one we've explored and found great information there for moving forward. Thank you so much.

ScibuddyAK - yes, the science teacher explained that would be our control for this project. Poor little seed sitting in a sea of perlite. LOL.

We've had to rework the systems a bit due to the water pump tubing being too wide and not realizing that the perlite needed to be rinsed first! But we got the systems back up and running last night so we'll add fish soon. Thank you very much for everyone's help!