Quick answer: A fish dome is a clear, upside-down dome that stays full of water above the pond surface. Air pressure on the pond pushes the water up into it, so no pump is needed. As long as the open bottom stays under water, the water stays in and fish can swim in and out freely.
The first time people see a FishView in a pond, the question is almost always the same: why doesn’t the water run out? The dome sticks out above the pond surface, it is full of water, and there is no pump. It looks like a trick, but it is the same physics you can try at the kitchen sink.
Fill a sink with water and push a drinking glass under, so it fills completely. Turn it upside down while it is still under water, then slowly lift it up. As long as the rim stays under the surface, the glass stays full, even the part that is above the water line.
That is exactly how a fish dome works. The dome is simply a very large, very clear upside-down glass.
The air around us presses on the pond surface. That air pressure pushes water up into the dome and holds it there. Inside the dome there is no air pocket pressing back, so the column of water stays in place. In theory air pressure can hold up a column of water of about 10 metres, so a dome of 18 or 45 cm is no effort at all.
The only rule: the open bottom of the dome must stay under water. If the rim comes above the surface, air gets in and the water flows out. That is why FishView stands on adjustable legs: you set the height once, so the rim stays under water and the dome rises above it.
The bottom of the dome is open, so fish can swim in and out freely. Many pond fish are curious and like to explore new spots, especially when there is something to see or find. In the dome they can swim up above the water line, which gives you a view you normally never get: your koi or goldfish at eye level, from the side, as if in an aquarium in the middle of your pond.
Every pond and every fish is different. Some fish discover the dome within hours, others need a few days. Our tips for helping them are in this article.
You will find every step with pictures in our gebruikershandleiding.
FishView comes in two sizes: the Standaard (Ø 25 × 45 cm, for garden ponds 45–90 cm deep) and the Mini (Ø 13.5 × 18 cm, for tiny, patio and bucket ponds). Read which size fits your pond.