Every reefer’s been there — acro-eating flatworms, red bugs, nudis, mystery bite marks that don’t add up. You’ve dipped in Coral RX, Bayer, Revive, hydrogen peroxide — and the pests still crawl out smiling. That’s when Spinosad enters the chat.

Spinosad is a soil-derived insect neurotoxin. It’s the active compound in Captain Jack’s Deadbug Brew and other ag-grade pest killers. It works by frying an invertebrate’s nervous system — they seize up, stop feeding, and die. It’s not gentle. It’s not “reef safe.” It’s the closest thing we have to a coral quarantine nuke.

The Ratio

The mix that’s worked for me is 1 ounce per 5 liters of saltwater — that’s roughly 0.75 ounces per gallon or about 22 mL per gallon.

Dip for 5–10 minutes with strong agitation. Keep the coral in motion. You’ll literally watch pests fall off dead. When you’re done, rinse the coral thoroughly in fresh saltwater — twice — before it ever touches your main system.

Don’t eyeball it. Measure it. This is the line between a clean colony and a bleaching stick.

What It Kills

Acro-eating flatworms. Red bugs. Nudibranchs. Eggs. Anything crawling that shouldn’t be there. Spinosad doesn’t discriminate — if it’s an invertebrate, it’s toast. It’s brutal, but that’s the point.

What It Doesn’t Forgive

This dip will kill pods, worms, shrimp, and sensitive LPS if you’re sloppy. Never use it in your tank. Never reuse the dip water. Wear gloves. Treat it like a chemical weapon, not a supplement.

Spinosad doesn’t care about your favorite wrasse or your refugium. It’ll nuke everything if it gets loose. Respect it or regret it.

Why Nobody Talks About It

Because it works too well. It’s not branded, not sponsored, and nobody can sell you a $40 bottle of it with a logo. It’s agricultural-grade and ugly — but it does what the fancy dips can’t.

I built my coral systems around precision, not guesswork. Spinosad fits that mindset. It’s for controlled, targeted destruction. You use it when everything else fails — not because it’s trendy, but because it’s final.

The Bottom Line

Spinosad isn’t for everyone. It’s not “safe,” it’s not gentle, and it’s not idiot-proof. But if you’re serious about keeping your reef clean — if you’ve dealt with the kind of pests that make you want to tear down a system — this is the tool that ends the fight.

Respect the chemistry. Rinse heavy. Stay lethal.