On 16/08/2014 23:33, Bob Hobden wrote:
"Spider" wrote...

I have been wondering about using Hydroleca as a substitute for
aquatic compost when potting up pond plants. There's probably a very
good reason why I've never heard of it being done, despite its being
used for hydroponics. Perhaps it's too light? I'd be interested in
other urglers' opinions/experience.


That is very light especially in water so any movement by fish and you
will have empty pots. The main problem is that it is nutrient sterile so
you plants will not grow well especially gross feeders like lilies not
matter how rich your pond water.
For lilies use good garden soil as long as it hasn't been
manured/fertilized recently, not even that "Aquatic compost" is good
enough for them without also buying their own fertilizer. (waste of
money IMO). The soil should be covered with pebbles but they must be big
enough and heavy enough that the fish can't move them and get in and
suck up the mud to feed. For Goldfish a goldfish sized pebble is about
right, for Koi no pebble is big enough, cover the pots with a wire mesh
wired down well but ensure the fish cannot get caught in the mesh but
the lily can send up shoots through it.



Thanks, Bob, you'd already made up my mind over the weight issue, so
I've abandoned Hydroleca for pond use.
Very interesting what you say about aquatic compost and lilies. I do
have a small lily in the pond. It's in its second summer with me and
has produced a flower bed, so I imagine there's enough food for now.
Maybe next year I'll have to pot it into better compost and, presumably,
a bigger pot? I have some reasonably good garden soil in the veg patch
which would suit, but I used chicken manure pellets on it this Spring.
Do you think it will be safe enough to use in the pond by next April, say?

As to my fish, they were rescued and given to me so, although I'm fairly
sure they're not goldfish, I don't know what they are. Definitely not
Orfe since I had those previously. It is possible, I suppose, that they
are small Koi. It's not easy to photograph them as they're not at the
surface for very long. I suppose I'll know they're Koi when they grow
too big for my little pond and start moving the plants about!

--
Spider.
On high ground in SE London
gardening on heavy clay