When a weed is not a weed and is in fact algae

Q. Just wondering if it’s possible to remove this weed from our dam, I have included some photos. Dam is approx. 40 metres long x 8 metres wide and only around 2 metres at its deepest. The weed is attached to the bottom and stays below the surface. The dam is used for watering garden and swimming.

Answer:

It’s a little hard to make out, but is it the same plant throughout? If yes, then what you’ve got is not a plant but actually a type of algae called Chara. Chara algae looks very similar to a plant but must in fact be treated as an algae.

Chara tends to grow in hard or alkaline waters. It does attach itself to the bottom of waterbodies, but not via roots as common in plants, but it secures itself to the bottom of the waterbody via a spaghetti like structure which helps to secure the Chara to the waterbody floor and is called holdfast. Chara grows densly and can easily cover the bottom of a water body.

The best option to treat Chara is an approved aquatic algaecide like Coptrol. Coptrol is intended for use in drinking water and irrigation water, so is ecologically safe.

To treat a dam of your size, I recommend at least 1.3L of coptrol. Since the Chara looks thick, I recommend using between 1.3L – 3L of Coptrol.

If you have fish we would recommend that you use our Coptrol Fish Pack.