Yes - a popular topic. :-( I realise that this is a FAQ, but technology
changes year by year, and I'm wondering what the latest views are.

I'm currently cleaning out our pond, for various reasons, but one of
them is that I want to have a real go at the damned blanket weed that
invaded several years ago, and finally got the better of us a year or
two ago.

I have drained the pond, and I'm scrubbing at the liner with a hard
floor brush, in an attempt to remove as much of the weed as possible.
It's almost *im*possible: traces of the weed remain no matter how hard
I scrub.

I'm aware that many "treatments" exist (I tried one a couple of years
ago), but do any of them actually work? I'm always afraid that it might
do for other things as well as the blanket weed. The one that I did try
(Tetrapond Algofin) had little discernible effect.

I suspect that the consensus will be: "put up with it, and try to
remove it regularly" :-(

Cheers
John

On Feb 9, 3:10*pm, Another John wrote:
Yes - a popular topic. :-( *I realise that this is a FAQ, but technology
changes year by year, and I'm wondering what the latest views are.

I'm currently cleaning out our pond, for various reasons, but one of
them is that I want to have a real go at the damned blanket weed that
invaded several years ago, and finally got the better of us a year or
two ago.

I have drained the pond, and I'm scrubbing at the liner with a hard
floor brush, in an attempt to remove as much of the weed as possible. *
It's almost *im*possible: *traces of the weed remain no matter how hard
I scrub.

I'm aware that many "treatments" exist (I tried one a couple of years
ago), but do any of them actually work? *I'm always afraid that it might
do for other things as well as the blanket weed. *The one that I did try
(Tetrapond Algofin) had little discernible effect.

*I suspect that the consensus will be: "put up with it, and try to
remove it regularly" *:-(

Cheers
John

The reason it thrives is nitrogen in the water. This comes from
rotting plant material, fish shit and sometimes runoff water going in
your pond. If you can run rainwater from the roof directly into your
pond (nothing dissolved in it) this helps by dilution.
If you have fish, there will always be nitrogen, the only way to
eliminate it is with a filter, bacterialogal filter and UV light
thingy. They sell the sort of stuff at koi shops. Now the koi thing is
passing you can pick them up fairly cheap, also 2nd hand.

On Feb 9, 6:42*pm, harry wrote:
On Feb 9, 3:10*pm, Another John wrote:





Yes - a popular topic. :-( *I realise that this is a FAQ, but technology
changes year by year, and I'm wondering what the latest views are.

I'm currently cleaning out our pond, for various reasons, but one of
them is that I want to have a real go at the damned blanket weed that
invaded several years ago, and finally got the better of us a year or
two ago.

I have drained the pond, and I'm scrubbing at the liner with a hard
floor brush, in an attempt to remove as much of the weed as possible. *
It's almost *im*possible: *traces of the weed remain no matter how hard
I scrub.

I'm aware that many "treatments" exist (I tried one a couple of years
ago), but do any of them actually work? *I'm always afraid that it might
do for other things as well as the blanket weed. *The one that I did try
(Tetrapond Algofin) had little discernible effect.

*I suspect that the consensus will be: "put up with it, and try to
remove it regularly" *:-(

Cheers
John

The reason it thrives is nitrogen in the water. This comes from
rotting plant material, fish shit and sometimes runoff water going in
your pond. If you can run rainwater from the roof directly into your
pond (nothing dissolved in it) this helps by dilution.
If you have fish, there will always be nitrogen, the only way to
eliminate it is with a filter, bacterialogal filter and UV light
thingy. They sell the sort of stuff at koi shops. Now the koi thing is
passing you can pick them up fairly cheap, also 2nd hand.- Hide quoted text -

- Show quoted text -

Growing plants, algae etc, will not eliminate the nitrogen, when it
dies it just recycles back into your pond. It is a closed sytem. The
only way to break it is by removing dead plant material, easier said
than done unless you MT the pond. And run a filter thing.

I suppose the first thing to do is to work out why your pond has a high level of fertility which gives rise to blanket weed year after year. We have had blanket weed in some years in one of our ponds, but with good plant cover and conscious attempts to reduce nutrient levels, it hasn't been too much of a problem. Last year, for example, we had a small amount a few weeks into the season, which I removed, and once the water lily leaves had developed we had no more problem.

The three ponds round the north side of the house don't get it at all.

What is your pond like? In sun or shade? fish or wildlife? What sort of plants?

Hi John, further to the very good replies, being an angler and now wearing my fishing hat, you may be interested in trying the following !!
Alot of commercial trout fisheries suffer from poor water quality due to the high nutrient levels from the trout waste etc. They get around this eutrification problem (which causes the algae ) by throwing into the water a bale of barley straw, so if you could get a pillow sized parcel of barley straw in a carrot net and place this in the water somewhere, it would do the same for you. There is one very important thing to know !! you must use straw that has been grown organically as some of the chemicals that farmers use to spray the straw, might have a detrimental effect on the pondlife.
No one seems to know why having this straw in the water effectively stops the growth of algae, but it is very effective !
hope this helps, Lannerman.

OP he

Thanks for all the *very* useful responses so far. (Notable that
nobody has recommended a "treatment" (i.e. from a bottle)!)

I think one of my main problems has been that there has been far too
much crud in the bottom of the pond for years, which may have provided a
nutrient factory.

We had fish for a while, but I gave them away when I realised they were
eating all the tadpoles and also all our snails. *However* I couldn't
catch one of the fish, and it stayed there for the last two years: I do
believe that that has had an adverse effect on the pond (which is quite
small - only about 3m by 1.5m by up-to-.75m deep). Unfortunately (for
it), the recent hard winter killed it, so that problem has gone away.

I've cleaned the pond, and I'm now filling it with water from the rain
butts. This new start, plus the advice received here, may help us
achieve a much better balance. I need a few more plants too, possibly:
the pond is in full sun.

Thanks a lot folks!

John

What I'd suggest, based on your further info, is:

1) don't change the water again, even if you do have more blooms of blanket weed. Try to keep the same water year on year. Balance isn't an instantaneous thing, it's something that develops.

2) try to cover at least a third of the water surface with leaves. Don't cover all the surface, as this will mean the water stays too cold over the summer and will affect your tadpoles.

3) you could try barley straw, which I've had no experience with

4) as well as the plants you are using to shade part of the surface, grow something fast growing that will mop up nutrients, and pull it up every now and again and put it on the compost heap (thus transferring the nutrients out of the pond and hopefully on to your vegetables). Watercress is a possibility, as is water forget-me-not. Don't pull them up till towards the end of the summer - my newts use the water forget-me-not for egg laying, folding the leaves around the egg.

In article ,
kay wrote:

What I'd suggest, based on your further info, is:

1) don't change the water again,...
2) try to cover at least a third of the water surface with leaves...
3) you could try barley straw, which I've had no experience with
4) as well as the plants you are using ...
Watercress is a possibility, as is water forget-me-not. ...

Brill - thanks Kay.

John

"Another John" wrote in message
...
Yes - a popular topic. :-( I realise that this is a FAQ, but technology
changes year by year, and I'm wondering what the latest views are.

I'm currently cleaning out our pond, for various reasons, but one of
them is that I want to have a real go at the damned blanket weed that
invaded several years ago, and finally got the better of us a year or
two ago.

I have drained the pond, and I'm scrubbing at the liner with a hard
floor brush, in an attempt to remove as much of the weed as possible.
It's almost *im*possible: traces of the weed remain no matter how hard
I scrub.

I'm aware that many "treatments" exist (I tried one a couple of years
ago), but do any of them actually work? I'm always afraid that it might
do for other things as well as the blanket weed. The one that I did try
(Tetrapond Algofin) had little discernible effect.

I suspect that the consensus will be: "put up with it, and try to
remove it regularly" :-(

Cheers
John

John when you come to refill your pond can I suggest you try and pipe the
rain water from your house roof and do not use tap water, also avoid using
any high nutrient soils in any plantings. using rain water greatly reduces
the amount of blanket weed that can grow

Make some fake lily leaves out of dark green plastic sheet and float them on
the pond until the real ones grow enough (helps to cut down on the light)

Use lots of plants you should able to see 50% or less water in summer

Good luck

--
Charlie, Gardening in Cornwall
Holders of National Collections of Clematis viticella
and Lapageria rosea cvs
http://www.roselandhouse.co.uk

In article ,
"Charlie Pridham" wrote:
....
John when you come to refill your pond can I suggest you try and pipe the
rain water from your house roof....

Yes, thanks Charlie. Don't worry: I've been an enthusiastic rainwater
collector since the drought of 1976 [when I was a toddler, natch. If
only.] With the aid of my mega-pump http://tinyurl.com/6lm5jq I've
re-filled the pond with the contents of three water butts [1]

I had iris sibirica in there, and also a water lily, both of which have
gone back in. I'll be adding water cress, as advised here.

What is *not* now in the pond, that was before, is half a ton of black
sludge, some of which dates back to previous ponds, and therefore 20-odd
years. Having always known that "sludge is good" (for small creatures,
natural organisms etc), I always encourage it. However I think I went
overboard, so I've cleared it *all* out, and will now allow a natural
build-up, which I'll keep on top of. [on top of which I will keep, to
paraphrase WS Churchill]

Other things which are no longer in there are (1) one ninja fish, which
eluded sight, never mind capture, for two years; the freeze did for it,
along with the fact that I accidentally allowed the whole pond to
freeze over, too thick, for too long: the water turned toxic. (2) 13
frogs, who also fell victim to my carelessness (3) no doubt numerous
smaller creatures such as dragonfly nymphs.

Pond enthusiasts will be glad to note that I carefully sieved the whole
"half-ton" of black sludge, looking for creatures.[2] A smelly business.
I found 6 live frogs, and two dead ones (the other eleven had floated
to the top already). I found NO nymphs, to my surprise. They usually
wriggle furiously and give themselves away in the slime: no wriggling
this time.

Finally: the plan is to let the pond re-start itself naturally (I am
confident of many frogs appearing shortly, and the tadpoles will have a
much better chance this year, without that damned fish around), AND THEN
to keep on top of blanket weed and other pests, with the aid of all the
advice I've received he thanks a lot folks.

John



[1] Hmmmm -- thinks -- that means my pond capacity is about 850 litres
-- never realised that before).

[2] Using a standard mesh garden sieve, into my plasterer's bath, which
has proved *invaluable* from time to time in the 20 years that I've had
it.

In article lalaw44-EF0675.16063413022011@surfnet-
nl.ipv4.ptr.145.109.196.x.invalid, says...
In article ,
"Charlie Pridham" wrote:
...
John when you come to refill your pond can I suggest you try and pipe the
rain water from your house roof....

Yes, thanks Charlie. Don't worry: I've been an enthusiastic rainwater
collector since the drought of 1976 [when I was a toddler, natch. If
only.] With the aid of my mega-pump http://tinyurl.com/6lm5jq I've
re-filled the pond with the contents of three water butts [1]

I had iris sibirica in there, and also a water lily, both of which have
gone back in. I'll be adding water cress, as advised here.

What is *not* now in the pond, that was before, is half a ton of black
sludge, some of which dates back to previous ponds, and therefore 20-odd
years. Having always known that "sludge is good" (for small creatures,
natural organisms etc), I always encourage it. However I think I went
overboard, so I've cleared it *all* out, and will now allow a natural
build-up, which I'll keep on top of. [on top of which I will keep, to
paraphrase WS Churchill]

Other things which are no longer in there are (1) one ninja fish, which
eluded sight, never mind capture, for two years; the freeze did for it,
along with the fact that I accidentally allowed the whole pond to
freeze over, too thick, for too long: the water turned toxic. (2) 13
frogs, who also fell victim to my carelessness (3) no doubt numerous
smaller creatures such as dragonfly nymphs.

Pond enthusiasts will be glad to note that I carefully sieved the whole
"half-ton" of black sludge, looking for creatures.[2] A smelly business.
I found 6 live frogs, and two dead ones (the other eleven had floated
to the top already). I found NO nymphs, to my surprise. They usually
wriggle furiously and give themselves away in the slime: no wriggling
this time.

Finally: the plan is to let the pond re-start itself naturally (I am
confident of many frogs appearing shortly, and the tadpoles will have a
much better chance this year, without that damned fish around), AND THEN
to keep on top of blanket weed and other pests, with the aid of all the
advice I've received he thanks a lot folks.

John


Sounds like you may have cracked it this time, hope so, ponds are one of
my favourite bits of a garden.

If without fish you find you have a problem with mossies, consider
introducing sticklebacks, too small to eat many tadpoles but they will
polish off any mossie lava (you don't of couse get to see them!)
--
Charlie Pridham, Gardening in Cornwall
www.roselandhouse.co.uk
Holders of national collections of Clematis viticella cultivars and
Lapageria rosea

We don't get any mozzies in our ponds - I presume the tadpoles get them.

If they don't, then the newts do (but newts aren't good for frog tadpoles ;-) )