Understanding Red Tide

For Florida boaters, a red-tide report is a reason to check current conditions before choosing a destination. Water color alone cannot tell you whether a bloom is present.

What is red tide?

Florida red tide is usually associated with elevated concentrations of the microscopic alga Karenia brevis. Its toxins can harm marine life and people. A bloom can discolor the water, but the water can also look normal.

What causes a bloom?

According to the Florida Fish and Wildlife Conservation Commission, Florida red tides develop offshore through interacting biological, chemical and ocean conditions. Once carried inshore, they can use nutrients from both oceanic and land-based sources. Blaming fertilizer runoff alone misrepresents that process.

Read FWC's red-tide FAQ for the scientific background.

Plan with official reports

Check FWC's current red-tide status and local advisories before heading out. Conditions change; going a few miles offshore or finding clear-looking water does not establish safety.

Reduce exposure

The Florida Department of Health advises against swimming in or around red tide. Airborne toxins can irritate breathing, and people with asthma or other chronic lung conditions may have worse reactions. Leave an affected area if symptoms develop and seek medical advice if they do not improve.

Do not collect or eat dead or distressed fish from affected areas. Check official harvesting status and health advice before collecting shellfish. See the Department of Health's current guidance for exposure and seafood information.

Keep engine care in perspective

Follow your outboard manufacturer's normal freshwater flushing and maintenance procedure. Flushmaster is an engine-flushing Controller; it is not a red-tide treatment or a verified method for eliminating algal toxins. Flushing equipment does not make an affected location, catch or swimming area safe.

Health and environmental guidance checked September 23, 2026. Use the linked agencies for current conditions.