The winter pond

The beast from the East brought an icy blast coupled with snow storms last week. Here in Moray we had an over night low of minus 11 which although pretty nippy for us, was still much warmer than some parts of Scotland, I heard that Braemar managed -22...yikes! The problem was that we have been in frost since mid January and at this time of year, my main concern is how my pond will cope with the severe weather and especially the aquatic life. A few months ago we had a flooding incident where the pond itself was under water and soil from the newly weeded bit poured into it. Then we had ice, solid ice and by midweek a fall of snow on top. Its always a priority to get a hole in the ice to allow the exchange of gasses that can build up in the pond from decaying vegetation and waste matter from the inhabitants or as I say, an air hole is needed to let out the frog farts. (I actually did google frog farts once but that's a whole different blog).

Its common practice to create a hole as gently as possible as its said that smashing the ice sends shockwaves that kills the inhabitants and especially fish, so my preferred method is to get a coffee can, fill it with boiling water and let it sit on the pond surface gradually melting its way through the ice.

We were relatively lucky in that the beast did only last a few days and when it did battle with the warm air coming up from the south we had gale force winds that created giant snowdrifts that cut off many roads in the North East, but for us, it meant that the snow got a quick shift and although its took a few days, the ice cleared from the pond. I pulled out my hot water can and was dismayed to find one of my fish lying dead underneath it. The can was in the shallow part of the pond where the fish don't generally tend to go unless they are spawning although the fish I lost last year was hovering around this area too. I assumed the worst thinking the low temps and frozen water had simply killed the fish and my thoughts turned to the other inhabitants of the pond. Over the winter I've been going out each evening with my head torch and been both surprised and delighted at the amount of frogs of varying sizes that have been living in both the fish pond and the wildlife pond. Luckily, it wasn't long before I could see the frogs moving about under the ice, diving down as my torchlight passed over them, and this gave me hope that the other fish may have survived.

I know I have written before about why I have both a wildlife pond and a fish pond and how the discovery of newts led me to dig the fish pond. You see, I was always told that if you wanted to have wildlife in your pond you can't have ornamental fish. Apparently fish are voracious and will eat plants, snails and pretty much everything else then can find. Also wildlife ponds are better with still water and if you have fish you have to have pumps and filtration systems that can be catastrophic for wildlife and I've read many an article of people clearing out mushed tadpoles from filters.

But...how much of this is actually true? Apparently Koi are devastating for plants, digging them up and muddying the water. When I tried to source fish for my pond I had no intention of using a mechanical filtration system and was told that I would need a five acre pond and at least five years for vegetation to establish to enable me to keep fish and have a good environment with clear water for them. I didn't believe that so began to google and found a host of YouTube videos of people doing exactly what I had planned to do and that was create a vegetative filter system. One of the key elements of using vegetation only to keep the water clear is simply not to over stock with fish and remember they do grow into the pond size. So with my pond roughly 6' x 3.5' ish and 2'6" at its deepest point, I put in 5, 2" sarasa comets, a pretty common variety of goldfish.

The first spring the pond water was like pea soup. It was awful. Occasionally you would catch a glimpse of a fish colour darting through the water but that was it. But the whole point of keeping ornamental fish is to enjoy watching them so I kept adding plants and also a few treatments of algae eating bacteria and wondered if it really would take five years to establish. No as it turned out. As the days became shorter and the sun not so intense on the water the pond cleared very quickly and stayed clear too, all the way through the winter and into the spring and the plants really took off and the fish were visible in the open water, but particularly enjoyed hanging around under the lily leaves.

So how does it work? Well its essential to have the right kind of plants. Under the water there are oxygenators, they are the lungs of the pond. Then there are the marginal plants that sit with their feet in the water and most of the vegetation above the water, these are the plants that really filter the water taking nutrients in directly from the water and the Iris is absolutely one of the best for this. Then there are the floating and rafting plants and these have a very important role at keeping the single cell algae in check by shading the surface of the water. In winter however, all of these plant functions are greatly reduced and when the pond has thick, opaque ice and a covering of snow, the light needed for photosynthesis. The ice also stops the movement of the surface water that creates a diffusion of oxygen from the air. A lengthy period of frozen weather can spell a disaster. As the ice has cleared over the last few days the remaining three fish have all been seen cruising the deeper level of the pond and that was a huge relief. They have reached quite a decent size and I am swithering whether to add a couple more to get back up to five or not...something to think about.

Incidentally, my friend who also has a fish pond, spent the icy days with a hammer, forcefully smashing the ice to bits and exactly opposite the advice given.... all of them have survived! Read more about the ponds in my garden here