# Is it a dino? | Algae ID

Source: https://algaeid.com/is-it-a-dino/

# Is it a dino?

Brown or red slime in a reef tank is usually cyanobacteria, diatoms, or dinoflagellates. Look at it through a hand lens or microscope and follow the chart. New to this? Start with [what a dinoflagellate is](https://algaeid.com/dinoflagellates/).

Follow the arrows. Click any result for details.

## How dinos move

Motion is the best clue, so take a video if you can.

The three main benthic pests, and how they move. Motion is the quickest way to tell them apart, which is why video is so useful.

**Not sure?** [Send me your photos or video](https://algaeid.com/contact/) and I will tell you what I think. And **do not start killing a bloom until you know whether it is toxic**: see the [safety notes](https://algaeid.com/treatment/#safety).

## Hints from the tank

Dinos often form a brown, amber, or red-brown film over sand and rock that comes off in strings and traps bubbles. Cyano is more often a red, purple, or black mat in low-flow spots, and diatoms a dusty brown coat on new tanks. The tank alone cannot tell you, but it is a clue.

![Brown film of algae over sand in a reef tank](https://algaeid.com/img/tank-dino-1.jpg)

Tank view of a dino outbreak: a brown film over the sand and rock. Image courtesy of a hobbyist.

![Brown film with trapped bubbles on sand](https://algaeid.com/img/tank-dino-2.jpg)

Another tank view. Bubbles trapped in the film are typical of dino mats. Image courtesy of a hobbyist.

## What tends to cause each one

[**Diatoms**A new tank or stirred-up sand, with plenty of silicate. Often temporary.](https://algaeid.com/not-dinos/#diatoms) [**Cyanobacteria**Low flow and high nutrients.](https://algaeid.com/not-dinos/#cyano) [**Dinoflagellates**Very low, often unmeasurable, nutrients; a new or sterile tank; few grazers.](https://algaeid.com/treatment/#ecology)

A rule of thumb from the outbreaks I have seen, not a law.

Why "algae" is not a useful word

It is a bit like saying "flying things": flies, bats, birds, and airplanes all fly, but they are not related. Cyanobacteria, red algae, green algae, diatoms, kelp, and dinoflagellates are all called algae, are only distantly related, and need different fixes. That is why the first job is working out which kind you have. If I was giving advice on dealing with a pest in your vegetable garden, I would have very different advice for dealing with rabbits as opposed to elephants, even though both are mammals.

Finding a dino does not mean you have a dino problem

When I look at sand from reef aquariums under a microscope, I can usually find some dinoflagellates. They are a normal part of the community, they cause no trouble, and you cannot see them without a microscope. In the same way, people often send me algae mats that are mostly cyanobacteria, and I can often find a few dinos mixed in. I would not call that a dino problem.

What matters is what is making up most of the bloom, the thing you can actually see growing in your tank. Only worry about dinos when they are the main contributor.

For a detailed guide to dealing with a bloom once you know what it is, see the [Dinoflagellate Guide](https://docs.google.com/document/d/127cKH5miePn4tsvzWNGNMuQivMh3fmxniPCVwLdF3ec/mobilebasic) (written by another aquarist) and my [treatment notes](https://algaeid.com/treatment/).