Your pond will need oxygenators to maintain a healthy ecosystem. These are plants, completely or partially submerged, which produce oxygen during daylight hours.
Like marginals, they will also reduce nutrient levels in the water, helping keep algal blooms under control.
Oxygenators are helpful for wildlife in your pond or stream too, providing shade, cover, egg laying sites, and - sometimes - attractive flowers for pollinators.
We supply two types of native oxygenator - Hornwort (pictured) and Water crowfoot. They both occur naturally acros the UK. We sell them in bunches of 5, with 5 strands in each bunch. We recommend using both types in larger ponds for increased biodiversity. Reckon on roughly 2 bunches per square metre of pond.
The bunches are clipped together with a metal clip (which you can see in the smaller photo), and just need throwing into the water rather than planting. They deteriorate quickly in transit so we ship them by First Class mail, and recommend getting them into water as soon as possible on arrival.
Native oxygenators are slightly tricky to grow, and have to be transported while in active growth. We offer two species, delivered between April and October. Deliveries may be subject to delay in the event of hot weather.
Hornwort (Ceratophyllum demersum): Hornwort is a healthy looking bushy plant which remind me of a fox's brush - hence its American synonym, Coontail. It grows in nearly all still water, from full sun to shade, and is found naturally in many places on the planet. It is fully submerged and grows in depths up to 60cm.
Water crowfoot (Ranunculus aquatilis): Water crowfoot is part of the buttercup family, and produces pretty yellow and white buttercup shaped flowers on stalks in late spring. They're regularly visited by a range of pollinators, incluiding bees and hoverflies. Water crowfoot will grow happily in ponds, or streams and rivers.
Please, please buy native rather than imported species like Parrot's Feather and Canadian pondweed. Not so much because non-natives might grow too quickly and aggressively for your pond - which is certainly a consideration - but because your pond plants can surprisingly easily escape into the wider environment (via birds' feet, for example).