A garden pond is a great way to attract all kinds of wildlife to your garden. Adding a feature such as a waterfall or fountain brings the pleasant sound of running water to your garden which in turn attracts still more wildlife.
This all sounds good but if you happen to be a tadpole or some other form of small pond life then things don’t look quite so good. The problem is water features require a pump to suck the water through, unfortunately it’s not just water that they suck up.
Most pond pumps have their main water suction hidden inside a protective grill to prevent larger objects such as bigger fish and debris from getting in the pump. Unfortunately most of these grills have holes too wide to prevent smaller pond life getting dragged in.
If you research it on-line you’ll also find stories of larger life such as small fish and newts perishing inside garden pond pumps and filters. Not good.
What Can Be Done?
There are pumps on the market that claim to be wildlife friendly. We had a quick look at the websites for these pumps but found the information unconvincing and minimal so we decided to try to find a home-made solution that utilises our existing pump.
What We Tried
Before we explain what we tried I should warn you that everything we do here is outside of any pump manufacturers recommendations. Anyone of these suggestions we mention could easily damage or destroy your pump. We decided to take the risk with our pump and it’s a decision you’ll have to take with yours.
1. A Stocking
Our first attempt was to use a stocking pulled over the existing pump case and tied tight with string to seal the stocking around the pump exit pipe and cable.
This appeared to work well at first, tadpoles were seen landing on the stretched surface of the stocking and swimming away without issue. But things soon took a turn for the worse.
After a few days silt began to block the fine mesh of the stoking material and as it did it caused the unblocked areas of stocking to concentrate the suction of the pump. As a result tadpoles began to get sucked on to the stocking and were unable to pull themselves away facing a demise arguably worse than that of being sucked into the pump.
It’s a nice simple idea, but it didn’t work for us.
2. A Bucket of Stone
Our next plan was to put the pump in a bucket and cover it completely with gravel the idea being that water will get sucked through the gravel but small pond life would not. We had high hopes for this idea as the gravel would pack tightly around the pump exit pipe and electrical cable creating an effective barrier.
Sadly, this too did not work.
The gravel needed to be sufficiently course that it would not get sucked into the pump so we tried both 10 and 20mm gravel to cover our pump. After we set it up it soon became evident that tadpoles were being sucked between the gaps in the gravel and on to the pump. This scenario was compounded by the fact that tadpoles love to wriggle down into the gravel to hide.
The other problem with this method is that you end up with a heavy bucket of stone sat in the middle of your pond that is incredibly hard to move. Not ideal.
3. Do it Yourself
Finally we resolved to build our own wildlife friendly protective cage to house the pump. The best thing we could find to do this were aquatic plant pots. These are like normal plant pots but the base and sides are perforated with a mesh of fine holes that allow water and nutrients to get through but prevent aquatic compost getting out.
The big challenge with this arrangement was always going to be how to close it up and get the pump hose and electrical cable out without leaving any holes through which tadpoles could gain access to the filter mechanism. This is tricky because tadpoles are able to get through surprisingly small openings.
We tried using two baskets put together to form an enclosed cage but finally settled on mounting the pump in one basket and closing it off with a square of filter foam cut to size and placed over the pot opening. Read on to find out how we did this…
Before we start here’s a diagram of what we did:
Of course all pumps are different, we were working with an Oase BioPress 4000 pump here but other pumps are likely to be very different; hopefully some of the information below will be of use in your case.
What we did
As you may be able to see from the above diagram the pump outlet emerges through a hole we made in the side of the aquatic basket. To do this we used a sharp craft knife to cut a hole as close to the size of the outlet as we could.
When doing this it is important to position the pump body so as to ensure that the suction intake of the pump is as central as possible to the middle of your aquatic basket cage. If it’s not and is too close to the edge of the aquatic pot then this will result in a suction ‘hot spot’ that could cause pond life to get trapped by the localised suction. The closer the pump intake is to the middle of the cage the less chance there is of this happening.
Once the hole is cut you then need to pass the pump outlet through the hole you created and somehow secure it in place. For this task we were lucky with our Oase pump as screwed to the end of the pump outlet was a removable adapter used to connect the pump to the outlet pipe. To mount our pump we just removed this adapter passed the pump outlet out through our hole and then screwed the adapter back on sandwiching the the aquatic basket between the pump and adapter and holding it in place.
To provide a flat, sturdy foundation for our filter structure we placed a heavy flat stone on the floor of the pond. We used a small paving slab but any flat, level stone will do the job.
On to this sturdy foundation we placed our home-made filter cage with the open side of the aquatic pond facing downwards. To provide a tight seal between the aquatic pot and the base stone we placed a square of aquatic pond foam between them.
NOTE: Only use proper aquatic foam, using foam from other sources may introduce toxic pollutants to your pond that could kill the wildlife in your pond.
Finally we placed a heavy stone on top of the aquatic pot which pushed it down into the foam layer creating a good tadpole proof seal between the foam and the flat foundation stone.
The added benefit of this weighting stone was that it lay a few inches below the surface of the pond and provided an ideal basking spot for the tadpoles away from the shallow edges of the pond where hungry birds lie in wait.
Total Wildlife Protection?
If you want to reduce the size of the holes in your aquatic pot still further one option we found effective was to coat the outside of the pot with sections of greenhouse shading mesh (ask at your local garden centre) stuck on with aquatic sealant. It’s a fiddly job but it adds an extra level of protection.
Any very small pond life smaller than the gaps in your pot will of course be susceptible to being sucked through the pump but in most cases their small mass will probably cause them to pass unharmed through the pump anyway.
If anyone out there has any other ideas to solve this problem please let us know using the comments section below.