Why Annual Cleaning is Bad

Why "Annual" Cleaning is ... BAD!
The Dirty Truth About "Annual" Cleaning - a.k.a. "Spring-Cleanouts"

Ponds and water features that only are cleaned once per year (also known as "spring-cleanouts") contain a full year's worth of sludge and muck that consists of detritus, mulm, fish waste, decaying organics, and algae.
As organics decay, toxic hydrogen sulfide gas is released causing foul odors and causes harm to fish gills.
Decaying organics feed algae.
Sludge is anaerobic (void of oxygen) which encourages harmful parasites and pathogens to proliferate.
Anaerobic conditions encourage harmful Aeromonas and Pseudomonas bacteria to proliferate.
Sludge is a breeding ground for Branchiura (Fish Lice), Lernaea (Anchor worm), Gyrodactylus (Skin fluke) and Dactylogyrus (Gill fluke) as well as harmful protozoa - Trichodina, Costia, Ichthyophthirius multifiliis (Ich, or White Spot), and Chilodonella.

"Annual" cleaning - commonly referred to as "spring-cleanouts" requires the catching and removal of all Koi and pond fish which raises their stress level, which lowers their immune systems.
"Annual" cleaning is a leading cause of Koi and pond fish disease and death.
"Annual" cleanings destroy the ecosystem - and requires a re-starting of the ecosystem.
"Annually" cleaned ponds and water features generate huge amounts of algae.