Hi Veggiejo is this a new pond? If so it will take a while to settle down. Do you have any other plants or wildlife in the pond or just the oxygenators and 2 snails?

Hi Moon, it is new - have a couple of plants and a lily. Thanks for your advice (was a bit worried cos its gone from looking really lovely to a bit green! Still I've had lots of visitors - loads of dragon flies and other winged creatures which is a joy to watch. That was the point of it really. Thanks again

Hi Vegg, as Moon says, it always takes quite a while for a new pond to settle down. The green water is caused by algae which are able to grow rapidly in the pond because of the high nutrient level in the new water. Once the nutrient level has fallen then the algae won't be able to grow and the water will clear, but it can take a season or two (at least) to get to that point.

Don't ever add tap water to the pond (unless it's a real emergency) as this is extremely high in nutrients.

Having lots of oxygenating plants will eventually serve to out-compete the algae (once they've got growing well) and they will take the nutrients out of the water for you.

A few surface growing or floating plants (Water Lilies or Water Hawthorn for instance) will reduce the amount of sunlight hitting the water, which will also impact on the growth of the algae. You want to aim for about 30% of the surface area covered with surface plants and 70% clear water to get the best balance.

Patience, above all, is the key!

You could also try a small pump running a fountain or waterfall to help keep ther pond oxygenated or even a couple of cheep bunches of oxygenators!