Cyanobacteria Chemiclean Protocol: Full Dose and Follow-Up

Cyanobacteria, that slimy bluish-green sheet that peels off substrate in sheets, is technically a photosynthetic bacterium rather than algae. Boyd Enterprises Chemiclean remains the most reliable knock-down for stubborn outbreaks, and a tight cyanobacteria chemiclean protocol wipes a tank clean in 48 hours when used properly. This walkthrough from Gensou Aquascaping at 5 Everton Park covers dosing, oxygen support, water changes and the cleanup that prevents an oxygen crash on day three.

What Chemiclean Actually Is

The active ingredient is generally accepted to be erythromycin or a related macrolide antibiotic, despite Boyd marketing it as a non-antibiotic compound. It selectively disrupts cyanobacterial protein synthesis without harming most fish, shrimp or higher plants at recommended doses. That selectivity is what makes it work where peroxide and blackout often fail against entrenched cyano mats.

When to Reach for Chemiclean

Use it when manual removal and a four-day blackout have not stuck, or when cyano returns within ten days of cleanup. A small patch on substrate is usually a flow or feeding issue and responds to a vacuum and water change. Sheets covering more than a quarter of your hardscape and substrate are Chemiclean territory. Our how to control blue-green algae piece covers the manual measures worth trying first.

Buying in Singapore

Chemiclean is stocked at C328, Polyart and a handful of Thomson aquarium shops, usually at $18 to $24 per 2 g sachet. Each sachet treats 380 litres at the standard dose. Carousell sometimes lists expired or repackaged stock at suspicious prices; the antibiotic loses potency over time, so buy fresh sealed sachets only. A back-up sachet on the shelf is cheap insurance for cyano-prone tanks.

Pre-Treatment Preparation

Twenty-four hours before dosing, perform a 30% water change and physically remove as much cyano as possible. Vacuum it out of the substrate, peel sheets off rocks and wipe the glass. Less biomass means the antibiotic does not deplete oxygen breaking down dead bacteria. Increase aeration by adding an air stone or angling the spray bar to break the surface; you will need that surface agitation for the next 72 hours.

The Dose Itself

Add one level scoop, the small one provided, per 38 litres of actual tank water. Dissolve the powder in a cup of tank water before adding to the sump or spray bar return. Skim off any protein foam if you run a skimmer; otherwise ignore the foam that may form on the surface. Lights stay on at normal photoperiod throughout treatment.

Oxygen Support During the 48 Hour Window

Dying cyano consumes oxygen rapidly, and an undersupported tank can crash to dangerous levels by hour 36. Add a backup air pump with a fine air stone, even on a planted tank that normally does not need one. Skip CO2 injection for the full 48 hours; the suspended bacterial debris reduces light penetration anyway, so plants are not photosynthesising at full tilt. Watch livestock for surface gasping and increase aeration immediately if you see it.

The 48 Hour Post-Dose Window

Resist the urge to water change for 48 hours; the antibiotic needs that contact time. Cyano sheets will turn from slimy green to grey-white and start lifting on their own. Carbon and filter floss should be removed before treatment so they do not strip the active ingredient. Refer to our how to fix cyanobacteria aquarium piece for visual reference photos of healthy versus dying cyano.

The Mandatory Cleanup Water Change

At hour 48, perform a 25% water change and reinstall fresh activated carbon. At hour 72, repeat with a 25% change and reinstall normal filter floss. By day five most tanks are visibly clear, although you will likely vacuum dead cyano out of the substrate for another week. Restart CO2 at half rate first day, then ramp back up by day three.

Why Cyano Comes Back

Chemiclean kills bacteria but does nothing about the conditions that favoured them: low flow zones, organic build-up, low nitrate combined with detectable phosphate, and overfed substrate. Audit each variable. A skimmed sand bed in a low-flow corner remains cyano-prone forever, so address dead spots with a small powerhead or repositioned spray bar. The aquarium water change guide we maintain is a good baseline check on weekly hygiene.

Reef Tank Notes

The same sachet treats marine tanks, but reef keepers see more stress on sensitive corals, especially Acropora. Run lights at 50% and skip dosing trace elements during the treatment window. Our reef tank algae control cyano dinos piece covers the marine-specific differences and what to do when cyano and dinoflagellates appear together.

When Not to Use Chemiclean

Avoid in invert-heavy tanks running freshly moulted shrimp; even macrolides can stress them. Do not redose within 14 days. If two consecutive doses fail, the issue is likely not classical cyanobacteria but something like dinoflagellates or a bacterial film, both of which respond to different protocols entirely.

Related Reading

• How to Fix Cyanobacteria Aquarium
• How to Control Blue-Green Algae
• How to Fix Blue-Green Algae Rocks
• How to Fix Blue-Green Algae Sand
• Reef Tank Algae Control Cyano Dinos