Deepening little pond.

[wuftytufty]

Hi,

I have posted before, but then disappeared, due to lots of work on the house needing sorting.

So we have cleared that and we are planning to work on the pond. We have decided to go whole hog and whip out all the stones that line it, dig it deeper and then line it.

So it is 5m (16ft 5in) long and 3.5m (11ft 6in) wide. Currently, when lined with big old stones, it is 45cm (17 1/2 inches) at it's deepest part. It has a waterfall going into the middle of one of the longest sides.

So my questions are:

When I line it, is it best to use paper & card, or sand or fleece? (It gets pretty cold throughout the winter here, so guessing lining might help?

How is best to stagger the depth. We have newts (mudpuppies) and frogs, so want to make it a good environment for them.

The pond is sort of sloping into the middle at the moment, I am guessing it is worth having one section which is a bit more sloped for the frogs and newts to climb out, but think I would probably look to create steps for the rest of it.

How deep should I go, given the current dimensions? I am thinking about 2 1/2 feet to 3 feet at the deepest point.


The main aim of all of this, is to provide a nicer environment for the fish (minnow tiny things), as currently, it keeps getting too much blanket weed algae choking everything up, it is a relentless job just pulling the stuff out all the time. The pond is in permanent full sun (no shelter) and being so shallow, I think the fish must be feeling like Boil in the bad rice in the summer, and probably not so nice for them in winter....

Since the chemical constitution of the pond is fine, and accepting that we will be adding more vegetation once we have deepened it, I am not too sure how to improve the pond anymore. Also, is it possible that there is too much oxygen in a pond?? Would that affect the growth of the algae!?! Also it blooms right after heavy rain, a lot, is this normal?

As always your advice is VERY helpful!

Attached are a couple of pics, so you can picture it....

Thanks,
Becky

 

[Waterbug]

When I line it, is it best to use paper & card, or sand or fleece? (It gets pretty cold throughout the winter here, so guessing lining might help?

Depends on the kind of liner used and soil condition. EPDM in many soils doesn't require any underlayment, but it's always good insurance. PVC really should have underlayment imo. A geo textile made specifically for this type of thing is of course best. Used carpet is good. Next would be newspaper and card board. I think sand is the worst because it moves under the liner, so rocks could cause some stretching.

How is best to stagger the depth. We have newts (mudpuppies) and frogs, so want to make it a good environment for them.

The pond is sort of sloping into the middle at the moment, I am guessing it is worth having one section which is a bit more sloped for the frogs and newts to climb out, but think I would probably look to create steps for the rest of it.

I don't really think these tiny creatures would really be able to understand that there was as section for them to get out, so they still could be stuck. For sure it would be more difficult. If your goal is primarily to support such creatures I'd slope all sides. Rocks, gravel, over the liner would help a lot too.

How deep should I go, given the current dimensions? I am thinking about 2 1/2 feet to 3 feet at the deepest point.

That's totally your call. We have ponds in the coldest parts of the US, much colder than Germany, that are 2' deep and fish survive. However, the deeper the pond the less the risk. Fish would love 15' deep, but that's normally unreasonable for the owner. I would say 3' in Germany would be more than fine.

The main aim of all of this, is to provide a nicer environment for the fish (minnow tiny things), as currently, it keeps getting too much blanket weed algae choking everything up, it is a relentless job just pulling the stuff out all the time. The pond is in permanent full sun (no shelter) and being so shallow, I think the fish must be feeling like Boil in the bad rice in the summer, and probably not so nice for them in winter....

The fish and other creatures love blanket weed. It creates a great base for a food chain.

What you're describing I call a Wildlife Pond. In a Water Garden or Koi Pond it would be important to remove all the blanket weed in the fall because the large fish, Goldfish and Koi, need a lot of O2 and the decaying organics are a problem. But in a Wildlife Pond many creatures depend on decaying organics to over winter. I'd kind of split the difference and just keep the blanket weed down.

Making the pond deeper sure won't effect blanket weed. Your best option imo is to construct the pond so removal is easier. Lilies for example make blanket weed removal very difficult as I'm sure you know. So maybe other plants in beds that make them appear to be in the pond, but not actually. Even lilies can be placed inside a concrete pot who's top is say 6" below the surface. Blanket weed will have a hard time growing inside the pot and easier to remove weed around the outside of the pot.

Also, is it possible that there is too much oxygen in a pond??

It's not possible.

Would that affect the growth of the algae!?!

Lot's of things effect algae growth. But I think people get a little confused. For example algae needs sunlight. And reducing light will reduce growth. The mistake is thinking reduced light will have any meaningful effect on the pond. The difference might be for example that with less light the pond becomes full of algae in 23 days instead of 22 days, or 20 days. Yes, it's a reduction, but you still have the same problem.

To actually eliminate algae is a separate issue. Reducing light and nutrients don't eliminate algae, only slows growth. Unless we're talking about 100% darkness and distilled water of course.

Also it blooms right after heavy rain, a lot, is this normal?

It's normal for algae to do whatever it likes. Because it was normal for this to happen in your pond it may stop in the future. Many species of algae. Always in flux, some grow, some die.

However, the main concern with rain is pH. Rain is pretty acidic, like 4-5.5 pH, and even down to 2. So if your pond doesn't have a good pH buffer (KH) the rain can crash pH. That can be harmful to fish but helpful to plants as it makes nutrients more available. Many people test for nutrients like nitrate, but even a high nitrate level doesn't mean plants can consume those nitrates. The level of pH is important. So it's possible the rain could make nutrient more available and you'd get more algae growth. But that's only a wild guess.

You have a pretty pond.

 

[dieselplower]

It does kind of look like this pond is in a low spot. Maybe runoff from the lawn into the pond is contributing to the algae? My frogs seem to be able to climb right up the tarp and flagstone that surround the tarp. They can climb out anywhere there want. No need for steps or slopes for them. They have very sticky webbed feet and can easily climb vertically.I am not a big advocate for many different levels in a pond. When modify my pond I will go from 3 levels to 2 and the plant shelf will be smaller than it is now, but packed densely. Having many different depths is like making steps for predators to wade into your fish buffet. My pond will go from an 18" shelf to 5'. Now it goes from 1' to 18" to 5'. Too many levels eat up space that could be used for more gallons of water.

 

[wuftytufty]

Hi, Thanks Dieselpower and Waterbug, for the advice, really appreciate it.

I will be keeping the rocks around the edge, so will put in a little sloping lip around the edge.

We just found and bought some appropriate fleece at the same time we bought the pond liner. The liner was heavy, we got the 1mm thick one, might be overkill, but figured with rocks around the egde, and wanting to get in it and wash it, it should be fairly durable.

Just to confirm that the pond isn't in a dip, it is a 2 level garden, and the edge of the pond liner is actually quite high, so there isn't run off into it, from the garden.

Thanks for the heads up on the shelfs, will keep it to a minimum, so one shelf about 8-10 inches wide and 18inches deep.

Thanks for the compliment on the pretty pond, we have fallen in love with it. When we bought the house, we were going to fill it in!!
Must go, dinner time!!

Re the KH, that was stable, but the PH is a little high, so if you have ideas about how to address that, I would be really grateful.

 

[dieselplower]

Please, do not wash the liner. All the stuff that grows on it is good for the pond. My favorite condition for my pond is clear water but liner covered with algae etc. Good stuff right there. It's my favorite because I love clear water, so that is kinda selfish of me, because a bit a green water is actually good for the fish. A nice layer of carpet algae on the liner is like a buffet for the fish. It also absorbs "pollution", like ammonia etc that could be harmful to the fish.

 

[wuftytufty]

Ok, I am guessing that I have to work on learning to live with "some" algae!

But not when it is taking over the pond!!

 

[dieselplower]

Ok, I am guessing that I have to work on learning to live with "some" algae!

But not when it is taking over the pond!!

I agree. At first i didnt it but then i learned it was good. I still remove any algae i can that is floating on the top.