In my last pond update, I showed you the shape of our wildlife pond after it was dug out and explained my thinking behind the design for the contours of my new wildlife pond. With the pond now all ready to set up, the next phase of our wildlife pond project is to prepare and install the equipment needed to make it all work!
- Oase sent me an Oase FiltoClear 31000 Set (which includes a filter – an Oase Filtoclear 31000 filter and pump – an Oase AquaMax Premium 16000 submersible pump) and a length of flexible tubing in exchange for an honest review and feedback on their products.
- I paid for and ordered all the other materials I’ve used in my pond.
- I’ve never received a payment from Oase.
- I don’t have any affiliate links in this article.
- There are no affiliate links anywhere on my website.
- I have not been told to say anything specific about these products – this post was written by me in my own words, expressing my own personal thoughts and feelings.
- I received one new Oase FiltoClear 31000 Set (which includes a filter and pump) from Oase, as well a length of flexible tubing that’s exactly the same as customers receive when they order these products online or in store.
- I don’t receive any commission from Oase (or any other company).
- Whether all of my readers choose to buy these Oase products (or none of you buy any) my personal finances are unaffected.
- I don’t hold any shares or have any financial interest in Oase.
- I don’t work for Oase.
- I have never received any payment from Oase.
- None of my family or friends work for Oase.
- I am simply passionate about nature, ponds, and wildlife, and I enjoy thoroughly trialling plants and products.
Equipment for my Wildlife Pond
When I set up my wildlife pond I used this equipment:
- For lining the pond:
- 9m x 8m of 1mm thick EPDM pond liner to line the pond
- Enough underlay to cover the entire pond, stream, and bog filter
- Additional pond liner and underly (4m x 8.5m) to line the bog filter and stream
- 25m of stone-faced liner to cover any exposed EPDM liner and to dress the pond edges and beach area
- For the water movement:
- An Oase FiltoClear 31000 Set, consisting of:
- An Oase AquaMax Premium 16000 submersible pump to push the water to the bog filter
- An Oase Filtoclear 31000 filter to pre-filter the water before it goes to the bog filter
- 20m of 50mm flexible tubing to connect the pump, filter and bog filter manifold
- Various clips and attachments for fitting the pipe, pump and filter together
- Various bits of guttering and other pipe to run the flexible pipe and power cords through, to protect them from being accidentally damaged by spades or digging in the garden!
- Sheets of wood and hinges to construct a box to cover and hide the filter
- An Oase FiltoClear 31000 Set, consisting of:
- For the bog filter manifold:
- PVC Pipes
- PVC joints and junctions
- PVC pipe cement
- Stone and aggregates:
- 1.5 tonnes of 8-10mm gravel/shingle to fill the bog filter and to line the bottom of the bog-beds
- 1 tonne of stone in different sizes to line the stream bed
- 12-15 large pieces of stone to make up the waterfall, stepping stone and other sculptural feature stones along the stream
- Various sized pebbles to dress and decorate the edges of the pond
- Various aquatic plants and marginal plants will be planted in my wildlife pond (more details in an upcoming article – see all my articles about this wildlife pond by clicking here).
Bog Filter Construction
In order to keep the water in our wildlife pond clean and healthy I was keen to incorporate a bog filter as part of my design for our wildlife pond. A bog filter is a natural water filter that works in a similar way to a reed bed filter. The construction consists of a manifold fed from the pump, at the base of a bed of gravel. The idea is that as the water is pumped into the bog filter under the gravel, the water will force its way upwards through the gravel, thereby leaving any detritus or organic matter from the pond held within the gravel. Aquatic plants are planted directly into the gravel in the bog filter; as the plants grow they take in the nutrients from the gravel and clean the water. Meanwhile, the now filtered water overflows over the surface of the gravel, down through the stream and waterfall, back into the pond. The bog filter naturally filters the pond water keeping it crystal clear.
The bog filter in my wildlife pond works in conjunction with an Oase Filtoclear 31000 filter, which pre-filters the water before it’s pumped through the bog filter. There are differing opinions on whether this is a wise design; there are some who believe that the bog filter should be enough on its own, and that if you pre-filter the water it can actually starve the bog of nutrients (since not enough of the pond detritus will actually make it to the bog filter). Others suggest that having both types of filter working together gives the best results and provides crystal-clear water, which benefits wildlife and aquatic plants.
I spoke to the experts at Oase to ask for their opinion on my pond design, they suggested that pre-filtering would ensure the smooth running of the pond with the added benefit of reduced maintenance over time; as the majority of the filtered material can easily be rinsed out of the mechanical filter. Whereas if I used a bog filter without an additional filter the bog filter would need to be dug out every two or three years to ensure the flow of water remains consistent. After digging out the bog filter, the gravel would need to be washed through before the plants and gravel could be put back – this is a considerable effort, which I’d like to avoid – hence my decision to combine the two filters. Whether the combination of the bog filter and the additional pond filter from Oase succeeds or fails, I’ll be providing regular updates to keep you up to date on the status of my wildlife pond – stay tuned! Click here to see every article I’ve written about my new wildlife pond.
Bog Filter Manifold
The manifold is the part of the bog filter which pushes the water fed from the pump, out into the gravel bed. With the bog filter manifold, the goal is to get an even distribution of water throughout the gravel bed of the bog filter, to avoid all the water (and therefore any filtered material from the pond) pushing through a single area of the gravel.
To construct the manifold, I designed a plan for a grid of pipes being fed by an inlet, using 50mm PVC pipes, and 15 bar pressure fitting PVC fittings for the corners and joints. In addition to the main ‘grid’ of pipes, I also added an upright pipe with a screw cap, designed to sit just proud of the water surface; if the filter manifold gets clogged up with detritus, this pipe can be opened up and the pressure from the pump will force any gunk out of this wider opening, flushing the manifold through without needing to dismantle the bog filter.
The pipes and joints were joined with PVC ‘solvent bonding‘ – which is a chemical bond that reacts with the two pieces of pipe, temporarily dissolving the PVC so that when the two pieces harden again they effectively become one, forming a permanent seal that is extremely strong. Once the grid layout shown in the plan below had been constructed, nearly 200 holes (each hole 6mm diameter) were drilled in sides of the pipes, to give an even distribution of water into the gravel bed.
This short video shows the bog filter manifold being tested with the pump connected, before it’s covered with gravel, to ensure a constant and even flow of water across the bottom of the gravel bed.
FiltoClear 31000 Set
I spent a considerable amount of time researching pond pumps to decide which make and model of pond pump would be best for the size of my wildlife pond to provide the optimum capacity for a decent flow rate for the stream and the bog filter.
To ensure I had the optimum pump capacity for my wildlife pond, I had to calculate the approximate volume of water in the pond, and then decide on the flow rate. My wildlife pond measures about 5.5m diameter, and about 0.7m deep (at the deepest point). Using the pond volume calculators available online, this gives an approximate volume of 16,000-20,000 litres of water in the main pond, plus the water in the bog filter and stream – so somewhere around 25,000 litres of water in total.
The experts at Oase gave me a lot of advice and recommended that I get an Oase FiltoClear 31000 Set. This is a combination set of filter and pump – in my case an Oase FiltoClear 31000 filter, and an Oase Aquamax Eco Premium 16000 pump, which has a maximum flow rate of 15,600 litres per hour. When buying a pond pump, you should never buy a pump based on its maximum flow rate. All pumps quote a maximum flow rate, which can be different from their model number. The figure for a pump’s maximum flow rate is measured at the outlet of the pump while it’s operating in clean water; however, as soon as the pump has a hose attached the flow rate will be reduced by the back pressure caused by both the head height that’s needed (the height above the water’s surface that the outlet of the hose will be at, and the friction generated as the water moves through the hose, and any other restrictions in the hose and fittings, such as the bog filter and manifold). Therefore, when determining pump flow rates and calculating what pump you would need for a system, getting the correct flow rate at the ”operating point”, normally the hose outlet, is the important part. Please be aware that all sorts of factors will affect the actual flow rate of the pond – in particular the diameter of the pipework through which the pump is driving the water, as well as the back-pressure caused by the filter, whether or not the filter is clean, whether there are any sharp bends in the pipes, and the restrictive effect of the bog filter manifold. The head height will also affect the flow rate of the pump – the higher the pump is having to lift the water, the harder the pump has to work, and therefore the lower the potential flow rate will be.
In my case, the flow rate at the operating point for my pond will probably be about 12,000 litres per hour, meaning that half the water in my wildlife pond will be recirculated through the pump, filter and bog filter every hour (providing the filter is cleaned reasonably regularly). This aligns well with the generally accepted recommendation of circulating the entire volume of water in a wildlife pond every four hours (NB: Oase’s recommendation for a fishpond is to turn the water volume over through the filters once every 2 hours (50% per hour) but for wildlife pond this could drop to once every 4 hours (25% per hour). This flow rate will also result in a good movement of water along the stream and over the waterfall, which will help with oxygenation of the pond water. It’s important to clean the filter regularly to maintain optimum flow rate and efficiency.
Aquamax Eco Premium 16000
FiltoClear 31000 Filter
The next stage of my wildlife pond project is to fit the pond liner, assemble all of this equipment, and then fill the pond with water and plants. I’ll show you this in my next update! See every article I’ve written about my new wildlife pond by clicking here.
For more articles about ponds, please click here.
For more articles about wildlife gardening, please click here.
To see all the articles I wrote about my old wildlife pond, please click here.
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