So this is what the pond looked like when I arrived. The pond is 2m wide, 6m long, and 2m deep. It holds 24,000 litres (~5.2k gallons), with the filtration and pipework capacity taking it to over 30,000 litres. Construction is by way of reinforced concrete base and walls set into the ground by ~1.6m, with the top ~0.4m sitting above ground.
The wooden decking on the left is essentially a lid that is raised using a pulley system. You can then walk down into the filter house, which is also set into the ground just like the pond.
The filtration system is gravity fed, which means there is a bottom drain in the pond. The water is pushed down the bottom drain, along some pipework, and up into a Nexus 310 which is a high-performance combination mechanical/bio filter. First the water is pushed through the mechanical filter section which removes dirt, grime, and weed etc. The water is then passed to the biological filter section which uses a filtration media, agitated by air lines, to foster friendly bacteria growth. This bacteria converts ammonia and nitrite (from carp poo) into harmless nitrate. The water is then fed, by pump, into a UV filter which passes the water through a tube under UV light which kills algae. The treated water is then returned to the pond through an outlet ~15cm below the ponds surface.
There’s also a skimmer system which filters contamination from the surface of the pond. Water that goes through the skimmer is then pumped into a ‘veggie’ or ‘bog’ filter (an additional shallow, gravel-filled pond, planted with moisture-loving plants). This section, located over the back of the main pond, is currently blocked off due to a leak – I’ll worry about this next year.
So, as you can see, it’s far from just a hole in the ground. I’ve spent loads of time online researching how all this stuff works, and spoken with the local koi centre, and the local pond builder. I’ve replaced a pump, and the UV bulb in the UV filter, trying to get the existing system working as perfectly as possible ready for winter. We have loads of trees, which means loads of leaves, and this could be a problem when autumn hits properly, especially with the skimmer system blocked off. I’ve purchased a massive fine mesh net to protect it this year and I’ll just chuck this over when the time comes.
In the coming days I’ll post about the best bit…… the fish.