Most sump pumps are cheap to buy. For intermittent higher pressure, higher flow situations a sump pump has a role to play in a koi pond. The running cost is high. When a retailer recommends sump pumps for a garden pond, say up to 6,000 litres (1,200 gallons) be careful … In fact in any situation where sump pumps are recommended then beware. This is what a typical sump pump looks like.
You can normally recognize sump pumps by their upright stance and by the fact that they suck the water in from the base (the black ring at base of this pump) as distinct from the side of the pump body like normal pond pumps.
In correct applications sump pumps like this did well The sump pumps outlet is the tangential pipe below the sump pumps valves in this diagram. This one was supplied with two way valves.
Consumers are often impressed when told how powerful such sump pumps are despite their low purchase price. What consumers are often not told is how very expensive these sump pumps are to run – this can be as much as what it costs to buy the sump pumps in the first place – and that cost is there EVERY year.
Unless you need to literally pump a sump out continuously or occasionally as many koi pond designs do require then avoid buying sump pumps.
The reasons are high total cost and low life expectancy in a continuous 24 hour operating mode exemplified by short life guarantees for sump pumps generally.
Over the years many Little Giant sump pumps have been used as pond pumps in my country. Today this company has very little market share left. A case of possibly wrongly specified product for the application.