Hi everybody!

I've been a keen freshwater aquarist for over a decade but I'm totally
new to outdoor ponds and I'm not sure whether the pond that our
landscape gardner is currently giving the finishing touches to is
actually suitable for fish.. a few words of wisdom from the experts in
this group would help me decide whether it's worth getting my hopes
up..

I'm interested in keeping Koi, but even a cursory glance over the
literature is giving me second thoughts about a few issues. Here's a
description of the pond:

Size: about 8 x 8m (24x24 feet)

Depth: around 50 cm ( 2 feet)

It is built with a liner on top of a generous layer of sand and the
sides are made up of a concrete block wall.

The whole thing will be covered by a metal grid to make it safe for
our baby. This should be placed an inch or so BELOW the water surface.

The gardner has already installed a fairly hefty multi-chamber filter
of (very) approximately 300L (60 gallon?) and an ultra-violet unit.

They've also currently planned a series of fairly powerful underwater
green lights.

A lot of things give me concerns there and this was clearly never
planned as a Koi pond..

1) depth: is it at all deep enough to keep koi or any other fish?

The filter will obviously be kept running during the winter months and
I imagine that this will help with the freezing. I also wouldn't mind
heating part of the pond with an immersion heater, but it might yet be
too shallow for a Koi and/or winter. I live in Luxembourg between
Germany and France, so we don't have Scandinavian winters but
temperature do occasionally drop under -10C.

2) metal grid/ child safety

Are Koi surface feeders? would I be able to feed them properly? will
it stress the fish?

3) lighting during the night?

I'm not sure yet how strong this lighting will really turn out to be,
but is this a problem for Koi?

I'd appreciate your thoughts...

Best regards,

Frank