Almost every planted tank goes through an algae phase, and the frustrating part is that “algae” is not one problem – it is a family of very different organisms, each caused by a different imbalance and each needing a different fix. Treating green spot algae like black beard algae, or black beard algae like cyanobacteria, wastes weeks of effort. This guide walks through the algae types you are most likely to see in an Indian planted tank, how to tell them apart, and what actually gets rid of each one.

Why Algae Appears in the First Place

Algae spores are present in essentially every aquarium all the time. They only turn into a visible outbreak when conditions favour them over your plants – usually some combination of excess light, unstable or insufficient CO2, and nutrient levels that are either too high or badly out of ratio. The single most reliable long-term fix for almost every algae type on this list is the same: get your plants growing vigorously and consistently, because healthy, fast-growing plants out-compete algae for the same light and nutrients. Everything else below is about correcting the specific imbalance behind each type.

Brown Algae (Diatoms)

What it looks like: A dusty, brownish film that wipes off glass, leaves and decorations easily with a finger.

Why it happens: Diatoms feed on silicates, which are commonly released from new substrate and tap water. This is why brown algae is almost a rite of passage in tanks under two months old.

Treatment: Wipe it off during water changes and be patient – it typically clears on its own within four to eight weeks as silicate levels drop and the tank matures. A few nerite snails or an otocinclus group will keep on top of it in the meantime.

Green Spot Algae

What it looks like: Small, hard, dark-green circular spots stuck firmly to glass, slow-growing leaves like Anubias, and hardscape.

Why it happens: Most commonly excess light combined with low phosphate, or inconsistent CO2. It particularly favours slow-growing leaves that stay in place long enough for spores to establish.

Treatment: Reduce photoperiod or light intensity, check that phosphate is not being stripped too aggressively by filtration media, and scrape it manually with a blade or a hard-edged tool – it will not wipe off like diatoms. If it consistently forms on Anubias or Bucephalandra leaves, our dedicated guide on removing algae from Anubias and other slow growers covers leaf-by-leaf cleaning methods that keep the rhizome undamaged.

Green Dust Algae

What it looks like: A hazy, bright-green film across the glass, giving the water an almost cloudy look; it wipes off into a fine cloud rather than a solid smear.

Why it happens: Similar triggers to green spot algae – excess light and nutrient imbalance – but green dust algae has a free-floating spore stage, which is why simply wiping the glass never seems to permanently solve it.

Treatment: The method that actually works is counterintuitive: let one full cycle run its course. Stop wiping the front glass for around three weeks so the algae completes its life cycle and releases spores, which you then remove in one thorough clean and water change. Wiping repeatedly during the cycle only resets it.

Staghorn and Green Hair Algae

What it looks like: Staghorn grows in stiff, branching grey-green tufts resembling antlers, usually anchored to leaf edges or hardscape. Green hair algae forms long, fine, stringy strands that drift in the flow.

Why it happens: Poor circulation, inconsistent or insufficient CO2, and ammonia spikes (often from overfeeding or a dead, decaying plant left in the tank) are the usual culprits for both.

Treatment: Improve flow to eliminate dead spots, stabilise CO2 injection if you are running it, and physically remove as much as you can by hand or with a toothbrush wound around the strands. Amano shrimp are genuinely effective against hair algae and are worth adding as an ongoing control measure once the root cause is fixed.

Black Beard Algae (BBA)

What it looks like: Dark grey to black tufted growth, often described as looking like a beard, usually starting on leaf edges, driftwood and filter outlets – anywhere with steady flow.

Why it happens: BBA is strongly linked to fluctuating or insufficient CO2 relative to light. A CO2 system that is inconsistent (running out mid-photoperiod, or turning on late) is the classic trigger, though it can appear in low-tech tanks with unstable flow too.

Treatment: This is the algae most worth fixing at the root cause rather than just removing, because it keeps returning otherwise. Stabilise CO2 delivery and timing if you inject it, increase flow near affected areas, and manually strip off badly affected leaves rather than trying to scrub BBA in place. It is one of the more stubborn types, so expect the fix to take a few weeks to show results.

Cyanobacteria (Blue-Green “Algae”)

What it looks like: A slimy, often blue-green to dark-teal sheet that forms over substrate or plant leaves and can be peeled off in one piece; it also has a distinctive musty smell.

Why it happens: Despite the common name, this is not algae at all but a photosynthetic bacterium. It thrives in low-flow, low-oxygen spots with excess organic waste, often in tanks that are overdue for a substrate clean or have a dead zone with poor circulation.

Treatment: Improve flow and oxygenation, gravel-vacuum thoroughly to remove built-up detritus, and manually siphon out visible cyanobacteria during water changes rather than leaving it to spread. A short blackout period (48–72 hours with the tank fully covered) is a well-established way to knock back a bad outbreak, though it needs pairing with the flow and cleaning fixes above or it will return.

Quick Identification Reference

• Brown, dusty, wipes off easily – diatoms, common in new tanks, usually self-resolving.
• Small hard dark-green spots, will not wipe off – green spot algae, reduce light and stabilise CO2.
• Hazy green film, clouds the water when disturbed – green dust algae, let one cycle complete before cleaning.
• Stiff branching grey-green tufts – staghorn algae, fix flow and CO2 stability.
• Fine stringy green strands – green hair algae, improve flow, consider Amano shrimp.
• Dark tufted “beard” growth on leaf edges – black beard algae, stabilise CO2 injection and timing.
• Slimy sheet, peels off in one piece, musty smell – cyanobacteria, improve flow and oxygenation, clean substrate.

Prevention That Works Across All Types

Whichever algae you are fighting, the same underlying habits keep it from coming back: consistent photoperiods rather than long or irregular lighting hours, a stable fertilising routine so nutrients are not swinging between excess and deficiency, and good circulation so no part of the tank becomes a stagnant dead zone. Fast-growing plants that compete directly for the same nutrients are also one of the best long-term prevention tools – see our guide on plants that help reduce algae for species that work well for this. Getting your dosing routine and your lighting right from the start prevents most algae types before they ever establish.

Frequently Asked Questions

Will algae eaters alone solve my algae problem?

Not on their own. Otocinclus, nerite snails and Amano shrimp help control existing algae, especially diatoms and hair algae, but if the underlying light or nutrient imbalance is not fixed, algae will keep regrowing faster than they can eat it.

Is it safe to use algaecide chemicals in a planted tank?

Most chemical algaecides are not selective and can damage sensitive plants like mosses and some stem plants along with the algae. They are best avoided in a planted tank; manual removal combined with fixing light, CO2 and nutrient balance is safer and more effective long-term.

How long does it take to fully get rid of an algae outbreak?

Most types visibly improve within two to three weeks of correcting the cause, but stubborn types like black beard algae and cyanobacteria can take four to six weeks to fully clear since existing growth needs to be manually removed while new growth is prevented.