Did you know that you can add a bale of barley hay to a 1 acre pond to help keep it from getting green and scummy in the summer? The hay, or possibly microorganisms in the hay, keep algae from overgrowing in the pond.

Algae are tiny, single-celled organisms called plant-like protists. They use the sun’s energy to make carbohydrates in a process called “photosynthesis” and they grow mostly in moist, sunny environments.

However, there are some places we don’t want algae to grow- like aquariums, or water purifiers. Some metals, organic chemicals, and other things (like barley hay) can keep algae from growing, or slow its growth. You can create your own experiment and discover some good anti-algae materials!

Take some lake or pond water and use it to fill several clear jars or glasses. Now, add a different non-toxic substance or item to each glass. Find things that you think might keep algae from growing. You might try pennies, tea bags, salt, vinegar, etc. Be sure to include a control sample, where you don’t add anything, so you can see normal algae growth. What happens if you cover glass one loosely with foil, so it gets air, but no light?

Place your samples in a warm, sunny spot for several weeks. You can lightly cover them with plastic wrap to reduce evaporation. Once you see green in your control sample, check the others. Did anything you add keep algae from growing? Did anything make it grow even better?