UV Filters Don't Control Hair Algae: Here's What Does

Hair algae (blanketweed) clings to rocks and waterfalls—UV clarifiers only treat free-floating algae in the water column. If you've got string algae, UV won't touch it.

Why UV Fails on Hair Algae

UV light only affects organisms that pass through the unit. Hair algae is attached—it never enters the UV chamber. Your flow rate over the waterfall is already marginal; adding UV plumbing may reduce it further.

Effective Hair Algae Control

1. Manual removal: Twist onto a rough stick or toilet brush—daily during blooms.
2. Nutrient reduction: Add more plants (especially floaters), reduce fish feeding, use barley straw.
3. Beneficial bacteria: Weekly dosing outcompetes algae for nutrients.
4. Hydrogen peroxide (spot treatment): 3% H₂O₂ applied directly to algae on rocks (1 cup/100 gal). Turn off pump 15 min. Use sparingly.
5. Algaecides (last resort): AlgaeFix (API) works but follow dosing exactly—overdose kills fish.

Fish in a 5-Gallon Bucket?

No. Even with plants and an airstone, a 5-gallon bucket lacks surface area for gas exchange, thermal stability, and waste dilution. Fish will stress and die within hours. Use a 100+ gallon stock tank or Rubbermaid tub for temporary holding.

Key Takeaway

UV = green water solution. Hair algae = nutrient/light management + manual removal. Don't expect one tool to do both.