TL;DR: Swim with more peace of a mind thanks to the 5Strands BlueGreen Algae Test, on sale for just $31.99 — an 8% discount — as of Sept. 24. The company claims its test can detect these toxic algae with 99% accuracy.

To swim or not to swim — that’s the question on everyone’s minds as the wrath of blue-green algae (a.k.a. pond scum) is at it again. For the last few years, the toxic algae showing up in bodies of water around the country has threatened the health of both people and dogs that come in contact with it. It’s been linked to higher risks of sickness (or even death) in dogs compared to humans, likely because they tend to swallow more water while swimming or playing.

Sometimes you can recognize this icky greenish sludge right away, but often it’s visibly undetectable. The only way to know for sure if a body of water is safe for you and your pets is to test it. And to do that, you’ll need a test like this blue-green algae test from 5Strands.

Brought to you by the same folks who make the food and environmental intolerance test for dogs, the blue-green algae test is quick and easy to perform. It uses a technique based on one of the most recent and breakthrough developments in hepatotoxin detection, which allows it to detect 11 commonly occurring hepatotoxins in a single test. It’s even capable of detecting levels below 0.1 microgram per liter. So, if there are blue-green algae afloat, it will detect it.

All you have to do is collect a water sample and wait about 10 minutes. The results immediately show you the current state of the tested water body, with positive or negative readings via a fluorometry-based visual guide. It will also show you the concentration of detected cyanotoxins. Two lines mean blue-green algae toxins were detected, while one line means you’re safe to play. The company claims that the results are 99 percent accurate. (Which is not 100 percent, but could be helpful.)

Keep your dog (and yourself) healthy and active for years to come by avoiding toxic algae. Snag the 5Strands BlueGreen Test on sale for $31.99 (regularly $35) for a limited time.