New pond... old sludge?!

[alex_l]

Hi all,

Our nature pond is getting a major upgrade from a reasonable size to a rather large 6.5m x 3.5m.

The liner is here, the digger is booked for Friday and the old pond is drained with all of the plants and sludge and critters in temporary homes, safe and sound. Not an ideal time of year to do it, I know, but we've made home from home habitats and everyone seems happy.

Anyway, we've pulled all the sludge from the bottom of the old pond and my question is should we transfer it to the new pond to mature it quicker?

I thought it was a definite yes... it's full of water shrimp, water louse and goodness knows what other inverts but the Internet is full of articles explaining how to remove sludge and stating all the problems it can cause, so now I'm unsure!

The new pond is to be 2' deep, with lillies, rushes and lots of oxygenators, unfiltered save for plants with maybe a small solar pump for a little flow and with stickleback and a pair of tench as the only fish, if this makes any difference?

Also, I plan to plant the plants up in our lovely topsoil capped with pea gravel rather than spending a fortune on aquatic compost... is this a bad idea? I don't want a pea-souper but I also don't want to pay though the nose!

Thanks

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[tam]

I'd add the sludge, or atleast some of it particularly as it sounds like you are aiming for a wildlife pond. I wouldn't add a foot of sludge back in, but if we are talking a layer over the bottom why not. It will re-sludge itself with time so you aren't adding something you would be safe from otherwise and as you know it's teaming with critters and the even tinier critters they feed off so you'll speed up the maturation process. Otherwise you'll have to wait for next autumn and the fallen leaves/dying back plants to sludge it for you.

Garden soil is fine, as long as you aren't the type to regular manure so it's full of fertilser.

 

[martin-green]

I wouldn't put the sludge back in, leave it near the new pond and let anything that moves to make its own way back, the sludge is dead and may deplete the water of oxygen.
Garden soil is often full of things you don't want or need, aquatic compost is sterile and doesn't float, it can be expensive, but it is worth it.

 

[mort]

My first advice would be go a little deeper than 2ft. It's a rule of thumb depth for cold winters but it doesn't allow much wiggle room, especially if you get a layer of mulm in the bottom. For a wildlife pond I'm not suggesting you go mad but just going slightly deeper can create more habitat. If you had 2 feet over the top of your water lily baskets for instance, it would provide a little more depth and allow the lillies to spread out a little further. Tench are lovely fish and if you are dead set on them I would perhaps go for 3ft depth as they can get quite chunky.

I'd add a little sludge but not much. It would depend on how long it's been in there and how processed it's been, if it's fresher then it could have nutrients you are better off without but if it's the older stuff that's been right at the bottom, it may be pretty inert. As it seems it's the life you wish to encourage then adding a little back will help seed the new pond but you could quite easily get the same thing when you add your plants.

 

[dw1305]

Hi all,

sludge from the bottom of the old pond and my question is should we transfer it to the new pond to mature it quicker?

I thought it was a definite yes... it's full of water shrimp, water louse and goodness knows what other inverts

I'd agree with @tam and @mort definitely put a portion of it back in. Ponds are highly productive environments, so it tends to build up fairly quickly.

the sludge is dead and may deplete the water of oxygen.

No, honestly it isn't dead, quite the opposite in fact.

Garden soil is often full of things you don't want or need, aquatic compost is sterile and doesn't float, it can be expensive, but it is worth it.

I wouldn't put any soil in, just some coarse gravel, and then <"let it get on with it">. I'm going to assume you have the Tench and Sticklebacks already? If you don't I'd leave them out. Newts will find your pond without any assistance and you will get alot more wildlife without fish. @foxfish is a fish pond whisperer, so I'll add him in.

but the Internet is full of articles explaining how to remove sludge and stating all the problems it can cause, so now I'm unsure!

The internet is full of people trying to sell you something. They will tell you that you need a pump, a bigger pump, a sludge buster bomb, deflocculant, algaecides etc. My advice is just ignore them.

cheers Darrel

 

[alex_l]

Thank you all!

I don't have the tench or sticklebacks, no... well we have a tench in with the koi but he shall stay there... he thinks he is a koi

I wasn't going to add any fish at all but was hoping I'd get away with stickleback if not tench as I was thinking they would be too small to eat amphibian eggs? But perhaps not?

We already have a colony of smooth newts so they take priority... we need to get them settled in safe and well.

Eesh... we can go down to 3' if needed... the lily I've chosen is suited to water up to 30"... it's going to be fun getting rid of the topsoil... but we've done it before.

@dw1305 would you not even add any soil for the waterlilies? I thought they were quite hungry?

I have a lot of plants to transfer so there will be lots of life reintroduced with those as well

Thanks all!

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[martin-green]

it's going to be fun getting rid of the topsoil... but we've done it before

 

[mort]

3ft was mainly if you have fish and I guessed since you mentioned them you are/were set on them. If you can be swayed not to add fish then it is the way I'd definitely go, you can't really have a true wildlife pond with them. Tench can get big and they are aquatic hoovers, great if you have a normal fish pond but not so great for the average wildlife pond. I truely love them and had a half dozen for over twenty years but I'd stick to them in the koi pond if you are happy to.

I don't always use aquatic soil either. I will if I have it but I would say the majority of the plants I've planted in my life have just been added in normal pots, if they even had a pot, with gravel borrowed from my brothers drive. I have used soil for water lillies and it's definitely one plant that is worth it but they will happily grow just tied to a brick and thrown in. It's not best practice but it's hard to not get plants to grow in a pond, often the problem is they grow to fast.

If you would like to get lost for a few days down the pond rabbit hole, and see how things can look if you really plan ever little detail, then this journal will wow the socks off you

Water meadow gardening

I guess like many on this forum, I have always been obsessed with water. I grew up in Holland spending most of my childhood fishing when I was not in school. Something about the water’s edge has always fascinated me and to this day, whenever I pass by a pool or a ditch, I just have to make my...

www.ukaps.org

 

[mort]

You can spread the topsoil over the existing borders, like a mulch. You would be surprised how much of the volume you can lose just by spreading it an inch or to deep over bare soil areas. Alternatively get some old sticks and logs, stack them and then put some soil over the top to make the perfect stag beetle habitat.
Another idea if you have grass is to mound some soil up and create a grass seat where you can over look the pond and enjoy your creation.

 

[dw1305]

Hi all,

I wasn't going to add any fish at all but was hoping I'd get away with stickleback if not tench as I was thinking they would be too small to eat amphibian eggs? But perhaps not?

Surprisingly fierce.

@dw1305 would you not even add any soil for the waterlilies? I thought they were quite hungry?

it's definitely one plant that is worth it but they will happily grow just tied to a brick and thrown in. It's not best practice but it's hard to not get plants to grow in a pond, often the problem is they grow to fast.

I do the same as @mort , but I'm always willing to trade long term stability for short term growth. It is the same as aquariums, low nutrients foster diversity and also give you longer before your pond becomes a swamp.

cheers Darrel

 

[foxfish]

Ha ha pond whisperer! Well I am no expert when it comes to liner built wildlife ponds as I only have long term, real life, experience with rigid and filleted ponds.

The main issue with a rubber liner ponds is just when they are getting mature, looking great and becoming low maintenance, they spring a leak!
I know that sounds a bit negative but, I am just sharing my experiences, I have lost count of the amount of leaking pond liners I have come across!

With a small pond, I think a rubber liner is fine but when you are talking about big, deep ponds, in my opinion not so fine.
However, there are of course always exceptions and if the pond is designed well, sited well, and has a suitable under liner, I am sure some will last for many years.
To be fair I am probably not up to speed on the very latest liner technology, so perhaps there have been some changes in the last 10 years that I dont know about.
If the soil is clay based you are far more likely too have more long term success than a stony ground base.
Certainly adding under felt is a good idea but obviously bumps up the cost.
I always use plain gravel to plant lilies as after a few years they will have burst out of the basket and the roots will be searching across the pond.
Where I live we have a good source of rounded edge gravel, be wary of anything sharp going in a liner pond, clay pots can break and sharp edge stone or gravel is not something I would recommend.

Having a deep area will offer a sump in case you need to drain the pond with a pump but, a sump will gather a lot of debris so be very aware if you ever have to walk in that area as a welly boot on top of a sharp stone is not good!
Also be aware that large shallow ponds will evaporate really quickly, a hot windy day can see a pond drop a couple of inches. If at all possible try to install a water main to an ball valve to keep the water level in place.
A lot depend on the pond shape and design but for the bottom of the pond I would use rounded gravel rather than soil, the gravel will quickly accumulate mulm and debris.

 

[sparkyweasel]

. it's going to be fun getting rid of the topsoil...

There is also this method;
Porridge

 

[alex_l]

There is also this method;
Porridge

Haha... prison techniques When my husband and I get rid of something little by little we call in 'Shawshanking' it, as in when he empties his pockets

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[alex_l]

Ha ha pond whisperer! Well I am no expert when it comes to liner built wildlife ponds as I only have long term, real life, experience with rigid and filleted ponds.

The main issue with a rubber liner ponds is just when they are getting mature, looking great and becoming low maintenance, they spring a leak!
I know that sounds a bit negative but, I am just sharing my experiences, I have lost count of the amount of leaking pond liners I have come across!

With a small pond, I think a rubber liner is fine but when you are talking about big, deep ponds, in my opinion not so fine.
However, there are of course always exceptions and if the pond is designed well, sited well, and has a suitable under liner, I am sure some will last for many years.
To be fair I am probably not up to speed on the very latest liner technology, so perhaps there have been some changes in the last 10 years that I dont know about.
If the soil is clay based you are far more likely too have more long term success than a stony ground base.
Certainly adding under felt is a good idea but obviously bumps up the cost.
I always use plain gravel to plant lilies as after a few years they will have burst out of the basket and the roots will be searching across the pond.
Where I live we have a good source of rounded edge gravel, be wary of anything sharp going in a liner pond, clay pots can break and sharp edge stone or gravel is not something I would recommend.

Having a deep area will offer a sump in case you need to drain the pond with a pump but, a sump will gather a lot of debris so be very aware if you ever have to walk in that area as a welly boot on top of a sharp stone is not good!
Also be aware that large shallow ponds will evaporate really quickly, a hot windy day can see a pond drop a couple of inches. If at all possible try to install a water main to an ball valve to keep the water level in place.
A lot depend on the pond shape and design but for the bottom of the pond I would use rounded gravel rather than soil, the gravel will quickly accumulate mulm and debris.

Hiya @foxfish

Ooh, lots of information here to take in

Okay so re the rubber, our koi pond has been in four years, 6' deep, approx 6 metres by four metres, I think. So a big old pond. No problems. That said, because it is both deep and sheer sided, there isn't much opportunity for anything to make contact with the sides.

The liners we use are EPDM. My husband is a manager at a factory that produces, of all things, rubber products so he's really au fait with the compounds and has full confidence in the EPDM. It's the same stuff they use for making belts with and it's 1mm thick. It'll be over generous underlay and our soil is beautiful soft, sandy loam.

However, I would be lying if I said I don't feel a little anxious about it, especially as we have a labrador who is know to get into ponds......... I will be having a sharp word with him the first time he tries... this pond needs to be off-limits. If the liner does fail, we will have to consider alternative methods... I'm not sure what! And at considerable expense, I'm sure! But cross that bridge if and when we come to it...

When you say you plant your lilies in gravel, is that straight into the bottom of the pond? As in, you don't bother with pots at all? It makes sense rather than constantly re-potting them. And you rely on the silt and the nutrients in the water column to feed them?

I have an ample source of pea gravel... around 5 tonnes, I'd say. It's small but round. We're taking up our old pea gravel patio to replace it with stone so it would be a good way to recycle some gravel! Would you use this across the whole bottom of the pond then, effectively as a substrate? Or does this increase the risk for puncture and make it harder to clean out debris in future?

How deep is deep for the sump area?

I like the idea of the ball valve... very clever and doable given the layout of our outdoor water feeds.

Thank you for the advice

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[alex_l]

@dw1305

Re: long term stability.. that's a good way of thinking of it! Thank you

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[alex_l]

You can spread the topsoil over the existing borders, like a mulch. You would be surprised how much of the volume you can lose just by spreading it an inch or to deep over bare soil areas. Alternatively get some old sticks and logs, stack them and then put some soil over the top to make the perfect stag beetle habitat.
Another idea if you have grass is to mound some soil up and create a grass seat where you can over look the pond and enjoy your creation.

I'm anticipating there may be around 8 cubic metres of so, based on previous projects... our soil seems very fluffy! Sadly my borders all are bark chipped so I can't spread on those but the lawn is in need of a good top-dressing so we could lose 2 cubic metres there, plus another on the veggie patch. We've managed to give literally tonnes away in the past to people although it always seems a shame to let it go! It's better than the bagged stuff... our garden has been gardened lovingly for almost 100 years and was farmland before that so it is the most beautiful loam!

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[alex_l]

3ft was mainly if you have fish and I guessed since you mentioned them you are/were set on them. If you can be swayed not to add fish then it is the way I'd definitely go, you can't really have a true wildlife pond with them. Tench can get big and they are aquatic hoovers, great if you have a normal fish pond but not so great for the average wildlife pond. I truely love them and had a half dozen for over twenty years but I'd stick to them in the koi pond if you are happy to.

I don't always use aquatic soil either. I will if I have it but I would say the majority of the plants I've planted in my life have just been added in normal pots, if they even had a pot, with gravel borrowed from my brothers drive. I have used soil for water lillies and it's definitely one plant that is worth it but they will happily grow just tied to a brick and thrown in. It's not best practice but it's hard to not get plants to grow in a pond, often the problem is they grow to fast.

If you would like to get lost for a few days down the pond rabbit hole, and see how things can look if you really plan ever little detail, then this journal will wow the socks off you

Water meadow gardening

I guess like many on this forum, I have always been obsessed with water. I grew up in Holland spending most of my childhood fishing when I was not in school. Something about the water’s edge has always fascinated me and to this day, whenever I pass by a pool or a ditch, I just have to make my...

www.ukaps.org

Excellent... I'll try and have a look at that over the weekend!

It sounds like I'm over-thinking the planting thing and I don't know why because with previous ponds, I've just chucked plants in!

I guess I thought I'd 'do it properly' this time as I've bought a fancy lily and what have you... but I suspect 'doing it properly' is overrated

I'm liking the idea of just gravel in pots... easy to lift and maintain... and low nutrients given that Darrel has made the point about lower nutrients being better in the long term.

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[Myrtle]

Re dogs in ponds: I have 5 dogs and when I built my main pond, I built a dog pond alongside to give them somewhere to use and avoid the temptation of the larger one. The dog pond is built with liner but the epdm liner is placed over thick underlay, then there's another layer of underlay over that, followed by several layers of el cheapo pond liner. This has worked well for 4 years so far with no punctures, despite my own dogs and neighbours dogs being in it, including 2 large labs and a kelpie!

 

[alex_l]

Re dogs in ponds: I have 5 dogs and when I built my main pond, I built a dog pond alongside to give them somewhere to use and avoid the temptation of the larger one. The dog pond is built with liner but the epdm liner is placed over thick underlay, then there's another layer of underlay over that, followed by several layers of el cheapo pond liner. This has worked well for 4 years so far with no punctures, despite my own dogs and neighbours dogs being in it, including 2 large labs and a kelpie!

I like it... I was thinking a substitute is the way forward and especially as he does only do it when he is warm and not just for the sake of it, so he needs somewhere for him

We've a second dog coming later this year so we've decided to fence a decent area of garden off and sacrifice it so the nice bit can stay nice... happily we have enough space to do this. So we will construct something in 'their' area. Although I don't envisage the new whippet following a labrador into a pond somehow

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[Myrtle]

Don't underestimate a hot sighthound! My whippet mix used to throw herself into water when she was hot in summer! She's too old for zoomies now, though!