"Harry Ziman" hziman at clara dot co dot uk wrote:

We are about to install a large pond in our garden. We don't intend to keep
fish in it, but do want to keep the water clear.

The advice we have received is that we need a UV clarifier to prevent algae
formation but, as there will be no fish, there is no need for a filter to go
with it. The algae will clump together and settle to the bottom.

However, looking here, it seems to suggest that a filter is needed - does
anyone have any experience and if so can you let us know. I don't want to
make an expensive mistake and install the wrong system.

Many thanks in advance.

Harry

If you put plenty of plants in, and don't have large fish, it should
sort it self out without any need of pumps and filters. I've twice built
ponds which have sucessfully done this. The first was quite small, 2 m
by 1m by 20 cm deep. Pretty much settled within 12 months.

The rather larger pond I now have (8 m by 4 m by 1 m deep) seems to have
stabilised this year for the first time - it's taken about 4 years but
is now packed with weed and crystal clear. To start with, I used quite a
lot of barley straw but so far this year it's looking very good all on
its own - despite have a lot of small bronze rudd, initially added to
keep down mosquitoes.

Earlier this spring, we had ~30 frogs who produce gallons of spawn.
Currently, common and palmate newts are very active. It's a major
attraction for birds and we even had a kingfisher and daubentons bat
last year. Last year also saw something like 8-10 species of dragon and
damsel fly.
--
Larry Stoter