Cyanobacteria Treatment with Chemiclean Guide: Slime Algae Cure

Blue-green slime that smells like a drain and peels off the substrate in sheets is not algae at all but cyanobacteria, a photosynthetic bacterium older than most vertebrates. Cyanobacteria treatment chemiclean guide hobbyists reach for first in Singapore is Boyd Enterprises Chemiclean, an erythromycin-based product that clears visible slime inside a week. This guide from Gensou Aquascaping at 5 Everton Park lays out the full seven-day protocol and, more importantly, how to stop the rebound that hits 70% of tanks within a month.

Quick Facts

• Target organism: Oscillatoria, Anabaena, and related cyanobacteria
• Active ingredient: erythromycin phosphate (Chemiclean brand) or similar macrolide antibiotic
• Dose: 1 scoop per 10 gallons (approximately 38 litres), single dose
• Course length: 48 hours, followed by mandatory 25% water change
• Rebound risk: 70% within four weeks if nutrient imbalance is not corrected
• Shrimp/snail safety: generally safe at label dose; observe during treatment
• Cost in Singapore: 2 oz bottle about $35 at reef and planted specialist shops

Confirming Cyanobacteria Before Dosing

Cyanobacteria forms flat, slimy sheets in green, red, or black, often covering substrate in low-flow corners. Peel a patch with tweezers; it lifts as an intact skin, unlike algae which fragment. The smell is unmistakable, earthy and swampy. Hair algae, staghorn, and diatoms do not respond to erythromycin and treating them with Chemiclean wastes money and nukes your beneficial nitrifiers.

Why Chemiclean Works

Erythromycin blocks ribosomal protein synthesis in bacteria, and cyanobacteria are bacteria despite looking like algae. The plant photosystems in your Rotala and Anubias are eukaryotic and unaffected. Nitrifying bacteria in the filter take a partial hit, so expect a minor ammonia bump during treatment and keep a test kit handy.

Seven-Day Treatment Protocol

Siphon out as much slime as you can without destroying the substrate, then raise aeration with an air stone for the full week. Dose one level scoop per 38 litres directly in the flow. Leave for 48 hours with lights on a normal schedule. Perform a 25% water change on day three and another on day seven, running fresh carbon for 24 hours after each. Visible slime dies off within 36 hours and sheets float up for netting.

Root Cause Analysis

Cyanobacteria colonises tanks with low nitrate (under 5 ppm), high organic waste, poor flow, and excess light duration. The bacterium fixes atmospheric nitrogen when dissolved nitrate drops, which is why starved planted tanks develop it despite looking pristine. In Singapore, tap water carries almost no nitrate, so a heavily planted tank on low-tech fertilisation often bottoms out within months.

Fixing the Imbalance

Dose potassium nitrate to keep tank nitrate at 10-20 ppm. Reduce photoperiod to six hours for a fortnight. Prune dead leaves aggressively and vacuum mulm from low-flow zones weekly. Add or reposition a powerhead so every corner sees at least some current; the dead spot behind a bogwood root is always where cyano returns first. These fixes matter more than the antibiotic itself.

Shrimp, Snail, and Biofilter Safety

Chemiclean at label dose is usually safe for dwarf shrimp, snails, and community fish. Reef keepers use the product with SPS corals in residence, albeit with heavy skimming. Watch for laboured breathing during the first 12 hours and add a second air stone if gill flare appears. Expect a cloudy bacterial bloom on day two as dying cyano releases proteins; heavy aeration prevents oxygen crashes.

Rebound Prevention Checklist

Test nitrate weekly for a month and dose to a minimum 10 ppm. Clean the filter intake and prefilter every two weeks to cut organic load. Replace bulbs older than 18 months; aged LEDs shift spectrum in ways cyanobacteria exploits. Quarantine new plants in a separate bucket with a dilute bleach dip (1:19, 90 seconds) to strip surface films that carry cyano spores.

When Antibiotics Are the Wrong Answer

If you have used Chemiclean twice in six months and the slime keeps coming back, the underlying nutrient or flow problem is unresolved and repeated dosing will eventually breed resistance or kill your biofilter. A three-day blackout combined with a full water change and manual removal is often more effective than a third antibiotic round. For shrimp tanks where any filter hit is intolerable, skip Chemiclean entirely and rely on blackout plus nitrate correction.

Related Reading

Green Water Aquarium Fix
Black Beard Algae Removal Guide
Staghorn Algae Treatment Guide
Green Spot Algae Removal Guide
Low-Tech Aquascape No CO2 Guide