Kidney Pond (3×1 ft) Green Algae Constantly

3 ft wide × 1 ft deep kidney pond, 4 goldfish, 1 pump, 1 lily. Cleans → green algae fast. Asks cleaning frequency, if dirty water kills fish.

Fundamental Fixes Needed

1. Pump must feed a filter with mechanical (pad) + bio media. Cleaning pad doesn't disrupt biofilter.
2. 4 fish in ~70 gal = overstocked. Reduce or upgrade.
3. Algae = sun + nutrients. Add plants (shade + uptake). Lily helps but insufficient.
4. Don't clean water out often. Bacteria live in water too. 25% monthly water change for nitrates.
5. Cycle the pond (Google "nitrogen cycle").

Dirty water stresses/kills fish. Fix filtration + stocking + plants. Cleaning is symptom management.