Skip to Main Content

How Can I Do a Jar Test for Pond Water?
Ask Our Pond Experts
Ask Our Pond Experts

How Can I Do a Jar Test for Pond Water?

Asked By: Margie of Clinton, ME

Creating a mini-ecosystem of your pond with a Jar Test will help you diagnose your pond problem. If you have green, tea-colored, or murky water, this simple pond water test will help you determine what is causing the clarity issue.

How to Jar Test Pond Water

Take a clear glass jar, dunk it in your pond, fill it with pond water, and let it sit in a dark place for 24 hours. Overnight, the jar stratifies and becomes a miniature version of your pond.

Interpreting Jar Test Results

Green Water
If the water in your jar is green or contains suspended green particles, you probably have algae. The source of nuisance algae blooms is often planktonic algae—floating, microscopic plants that color pond water green, blue-green, brown, or variations in between. To clear things up, learn  how to get rid of algae from our experts.

Tea-Colored Water
Beige or tea-colored water means you have leaf tea brewing in your pond. As organic debris decomposes, tannins and other byproducts steep and discolor the water.

Your first remedy is to add a bag of Activated Carbon to the water. It will clear up the dissolved materials that are causing the problem. While the carbon is working, remove floating and decaying material with a skimmer net or use the ClearVac Pond Vacuum. Keep your pond clean by skimming it regularly and covering it with pond netting during the fall months.

Clear Water With Sediment
Does your jar have clear water with a layer of sediment on the bottom? If so, you have an abundance of organics in the pond. When your fish play and forage for snacks, they stir up debris and cloud the water. Here is an easy four-step water treatment plan to get you started:

  1. Remove large debris.
  2. Perform a partial water change.
  3. Add Water Conditioner.
  4. Double down on the Beneficial Bacteria.

Pond Water Testing Advice

A jar test can reveal a lot about the water in your pond. If you need assistance determining what your jar is telling you, call us at 866-POND-HELP, email us your Jar Test photo at, or use our contact form.

Check out these related water quality and testing articles for water gardens, ponds, and lakes:

How to Clear Brown Pond Water
How to Fix Foam in Pond Water
How to Lower pH in a Pond
Muck Control
Turbidity in a Pond Explained

Last Updated: May 14, 2024