Pumps and Filters for your Garden Pond - Second filter rebuild

Basic considerations      First filter rebuild      Final filter rebuild      


Having decided to make the pond so much larger than it was, there were a number of things that I would need to consider. By giving my fish more room to grow, they would grow to fit their new environment and their waste output would be significantly increased, especially as I now had half a dozen Koi in the pond. Coupled with that, the increased surface area would catch much more dust from the air. My filter was going to need to be cleaned much more often and may even have to be enlarged. Once more, "management" approval was sought and we decided that if the filter needed to be cleaned out more often, then we had better try to make it easier to do. Although, I had fitted a drainage valve, it still wasn't easy to clean it and I still had to spend a fair amount of time leaning into the box with a small bucket. I had also seen the new generation of vortex filters and wondered if I could incorporate one into my system to remove some of the debris before it reached my main filter.

The idea of the vortex filters is that the water is pumped into a round chamber at a low level and at an angle which forces the water to begin to spin and then the output is taken at almost the top of the chamber. The chamber needs to be big enough that the water moves relatively slowly and, in this way, all the heavy particles will fall to the bottom of the chamber as the water turns so that the water that flows out of the chamber is much clearer than it would otherwise have been.

If I was going to be able to do that, I would have to redesign the top of the garden as well, which meant even more work and planning. I would have to remove my top pond, and raise my existing filter to above ground level so that it could connect with the vortex. I would also need to work out how to drain both filters without too much effort.

Once more working in the winter months so that I could safely leave the filter off for however long it to to carry out the rebuild, I first built my new filter in the garage. I spent some time at the local garden centre checking how the commercial boys made their filters and once I was happy, I dismantled the top of my garden and dug out my existing filter. Once I had worked out the design of the conecting pipework and built the new system dry in my garage, it was time to set it up in its operational position. The total weight of the filter system when it is full of water will be almost half a tonne so the base had to be able to support it whilst protecting the waste pipes. I used the concrete slabs that I had recovered from my old top pond to shape the base. I infilled the frame with a mix of earth and rubble to prevent the slabs from falling over.  Top

The pipework had been put together in the garage. All the components were bought from the Rose Cottage Water Garden Centre near Spalding in Lincolnshire and as usual were the cheapest in my area. I decided to use solvent weld pipe as I didn't expect to see it again once the filter was complete. The plastic covers over the open ends of the pipes are there to prevent any debris getting into the pipes and fouling the gate valves.

The pipework that you see here will enable either the filter box or the chamber to be emptied for cleaning withiout necessarily having to clean both at the same time. The gate valves are very simple to use and are much easier to manipulate with very cold hands if cleaning needs to be done during the winter.

With the pipes confirmed in place, they were covered with gravel to provide some additional support to the base whilst protecting the piping. Then the filters were put into position and connected to the waste pipe system. The connectors protruded into both filters by about 5cm so I had to find a way to raise the base of both filters to be flush with the drains to allow for easy emptying.

I fitted a spare piece of pipe into the drains and covered the pipe ends before filling each box with water to the level of the drain. I left the ssystem filled with just that amount of water for a couple of days to ensure that the sealing of the pipes was perfect. Then I poured rapid setting concrete (normally used to set fence posts) into the water. Within a few minutes the concrete had begun to set and by the end of the day, I was able to remove the spare pieces of pipe to reveal a smooth flat base with a flush drain in the middle of each filter. I left it another day to complete its hardening before continuing.

As you can see from the pictures below, the filter looks quite precarious on its support but as you'll see later, I wanted to be able to build a block wall as close to the filter as possible so I needed to be able to build a base for the wall. Even without any extra support, the vortex filter worked first time spinning the water up through the water butt and over the collector and into my old filter box. My new pump had a regulator valve which allowed me to adjust the water flow to the optimum rate for my new system.

So there I was with my new filters working well and I was able to clean them in less that 15 minutes. I've lost count of the number of times that I used to curse the time it took when it was cold, wet and miserable. So I was delighted with my new system.

The only trouble was that the filters were right outside the kitchen window and "management" didn't really appreciate the view. So I decided to build a wall around them, partly for protection for the filters but also to try to make the whole thing look a bit better. As I was going to be mixing cement for the wall and buying the blocks, I decided to build a little pond / stream to take the output from the filter back to the pond. The pond would be very shallow so that the birds could come to bathe and I would be able me to grow some clourful pond plants up near the house. By taking the output pipes from the filter straight down to the level of the new pond and then turning them through 90 degrees so that they were now inside the liner before going to various points across the pond, I was able to create the illusion of springs amongst the plants.

My original intention had been to build the whole thing using the decorative blocks but they were too expensive so I used the building blocks and intended to render them and paint them a colour suitable for the garden. Unfortunately, I never did get the rendering done and the bare block wall was soon being referred to as Pill Boxes. Management was not best pleased but as my filters were working well and I couldn't see anywhere else that they could go, we had to make the best of things.

And that's how things remained. Over the next few months, we gradually got used to the Pill Boxes though, to be honest and don't let management know, I didn't like them any more than she did.

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