Inherited wildlife pond, help please!

[Backseatponder]

Hi, My parents have just moved into a bungalow where the previous owner kept Koi carp in a pond. They do not want to keep fish and we are therefore turning it into a wildlife pond which much more suits their garden ethos, so we are on a steep learning curve and I have learnt a lot from your forum thank you! The pond had not been maintained for a number of years as the previous owners aged and there are no fish left The algae bloom came in spring but never went and is now quite thick. We had mating frogs (now tadpoles), there are a lot of snails, plenty of water bugs and the odd newt and much more I'm sure. The plants in there are water lilys, a marginal small reedy plant and the oxygenator myophallum brasiliensis (parrots feather) which I know is non-native and invasive. They only cover about 30% surface which I think is why the algae is so prolific.
My plan is to add a native milfoil to cover surface, oxygenate and compete with algae and when that is established start cutting the Parrots feather back/out. I will also add Barley straw. I saw an advert for Eco Sure microorganisms that get rid of algae in 2 weeks but not sure if that is necessary/good idea.
More long term plans include hooking up a hose pipe to the roof water butts to channel rain water into the pond, and replacing all plants with native species.

My questions are; 1. How much of a problem is the algae and are we clearing it appropriately? 2. do we need to use an aerator eg solar powered with there not being many oxygenators below the surface at the moment? 3. since lots of leaves have gone in without being cleared should we clear any silt (there's no more than about 10 cm)? 4. Have I missed anything?! Any advice greatly appreciated, thanks so much for reading.

[GCN lova]

hi ,

i think you're doing a great job. the frogs and newts should have easy access to and from the pond. you are doing the right thing in using barley instead of chemicals. for blanketweed you should stick a cane in there and twist it around and pull it out. leave it overnight so animals can crawl back in the pond! the algae is not much of a problem unless the blanketweed covers the surface. the tadpoles and snails should keep it in check .

GCN lova

PS: welcome to WAB

[Backseatponder]

Great, thanks! The algae is just single celled free floating algae so I guess it's not so bad!

[King Edward]

Could you post any photos of the pond? And how large/deep is it?

What kind of algae are you having problems with - filamentous (blanketweed) or single-celled (green water)? Either way, I suspect the ultimate cause is high nutrient levels in the pond perhaps as a result of long-term fish feeding (amongst other things). Barley straw might help as a temporary measure, but you really want to sort out the underlying problem else it will recur. Using rainwater will definitely help, but you would probably want to remove a lot of the sediment as well since nutrients will have built up here and will continue to be released back into the water.

It's tricky since you don't want to cause too much disruption to the existing wildlife, but improving the water quality would benefit it in the long run. Replacing the existing plants also sounds good, although I don't know how easy it is to remove Parrot's Feather bit by bit.

Regarding your question 2, you shouldn't need to aerate the pond if the water quality's good - even without plants a lot of oxygen should diffuse in from the surface.

Edit: missed your reply there. Essentially, it's best to sort out the underlying cause of the algal bloom rather than just treating the symptons.

[Backseatponder]

Hi, thanks for your advice! The pond is kind of guitar shaped, approx. 8 m by an average 3 m. and 80cm deep in the deepest part. It has 3 shallow shelves which amount to about 35-40% of the surface area. I estimate it to be around 3-5,000 liters.
Regarding the sediment, I have seen hoover type things that suck out the sediment from the bottom of the pond, do you think it would be worth sucking the sediment out? Would I need to leave some behind as it seems to take a while to build up and I know a lot of things live in there?

[Tursiops2]

If I were in your position, I'd be giving serious thought to re-doing the whole pond from sratch - draining, clearing out all plants (it's the only way to be sure of removing all the Parrotsfeather), binning the old liner (it must be past it's best by now), re-shape the bottom to create shallow areas, re-line, fill with rainwater, and re-stock with plants. It could save you a lot of faffing around in the long run.

T2

[Backseatponder]

Hi. Thanks for your ideas! I'm not too keen on doing a total rehaul mainly because my parents have a lot else to do and it's quite a major job. They would possibly decide to just fill it in which would be a real shame in my opinion as there is so much life in and around it. However it is something to consider, I will research more about how it is done, would I have to wait until autumn when the tadpoles/frogs etc have moved out?

[GCN lova]

that would be the best time (before it snows and after the wildlife has started to hibernate) but newt larvae may still be around and some hibernating frogs will stay at the bottom of the pond.

[King Edward]

Autumn is generally considered the least disruptive time to clear out a pond, but in the long run it probably doesn't make too much difference. So long as you wait until the tadpoles have left then I think during the summer would be OK. Adult frogs and many of the other creatures would be well able to find new homes then, whereas during the winter they would probably be more sensitive to disturbance and less able to relocate.

Considering that you seem to have a serious algae problem, I would probably drain the entire pond and remove the sludge using buckets / wheelbarrow as required. It would be drastic, but probably more satisfactory than trying to improve things bit by bit. Sediment on the bottom does tend to accumulate fairly quickly in a new pond, especially if you have leaves going in.

How shallow are the shelf areas?

[dampflippers]

Are you able to upload any photos? That would be a big help.