Persistent Green Water: Biofilter Missing, UV Alone Insufficient

300-gal pond, 4 fish (24" total), Laguna pump + Pressure-Flo 700 with UV — still green. UV clarifies; biofilter cleans. You lack biological filtration.

Why UV Isn't Enough

• UV kills suspended algae → clumps → must be filtered out.
• Pressure-Flo = mechanical + UV, **weak biofiltration**.
• No bio-media = dead algae recycles as nutrients → new bloom.

Fix: Add Real Biofiltration

1. Add biofilter: Aquascape BioFalls, OASE BioSmart, or DIY moving bed (K1 media).
2. Plant heavily: Submerged (hornwort), marginals, lilies — 60% cover.
3. Add rocks/gravel in pond: Surface area for bacteria.
4. Bacteria starter: Weekly for 4 weeks.

UV Reality

• Second UV won't help — same dead algae, no filter to catch it.
• UV bulb replaces yearly — even if glowing.

Green water = biofilter gap. Plug it. Plants + bio-media + bacteria = clear water.