Please Help, overgrowing pond weeds blocking filters and taking over

[christopher kazamias]

Hi guys, I'm having a bit of a nightmare with my garden ponds.

We started them about three years ago, the last couple of years they have been great. I've had a collection of frogs spawning tadpoles, newts, dragonflies and other lovely natural life. I have a few goldfish in each pond (I have two small ponds) and these have been fine.

This year I was away the six months and when I got back the ponds were quite dirty as the filters hadn't been running.

Sadly even though the frogs laid lots of spawn none of it hatched as I think the ponds were too dirty.

On my return I cleaned the ponds and got the filters running and everything looked okay and the water cleaned up nicely

However in the last few months both of my ponds have been having a lot of problems with weeds growing. I'm not exactly sure what type they are, it seems like maybe blanket weed in both ponds and another type off plant growing in one which looks more like a firn. The water itself has been pretty clear, as long as the uv filters are running, however the weed keeps blocking the filters. Yesterday I found one of the ponds almost empty. I'm not quite sure how this happened, it's possible that the filter which has a fountain spray tipped due to all the weeds and sprayed al lot of water out.

I don't want to do a full clean and empty as I don't want to disturb the newts and other life in the Ponds. How can I get on top of this weed issue? I've been pulling them out every few days but they now seem to come back as quickly as I move them. The garden gets lots of sun which I don't think is helping.

Are there any products I can use that wont harm the animals living in the ponds?

Any help really appreciated. I've included some photos of the ponds today.

It's all a bit depressing.

Regards.

Chris

 

[tbendl]

The walls and filter look like string algae but it looks like anacharis in your hand. The string algae can be cleaned out using a toilet brush but the anacharis is a good plant to help keep the algae under control. I have heard people using a peroxide/water mix to get rid of the string algae.

 

[christopher kazamias]

Thanks you are right it does look like string algae. Is peroxide dangerous for the wildlife in the pond? Also I just tested my water ph and its at about 8.5/9. Should i try to bring this down?

 

[tbendl]

The peroxide is safe for wildlife, I don't have fish so I never test my water and don't know. It looks like you need a lot more plants to out compete with the algae. Do you have any additional pictures? I had an algae bloom this spring, (not string) but ended up having to use batting with a small pump to get the fines out of the water. I would assume you will need to do the same thing. Do you have accumulated gunk on the bottom of the pond or is it free from sediment?

 

[tbendl]

The Pond Industry is fraught with 'Snake Oil' salesmen.
There are very, very few pond treatments available that prevent a problem, they usually claim to treat the symptoms and do not always even do that very well.

If you have an overabundance of filamentous (string) algae it is because of a high Phosphorus level in the pond's water. Sources of Phosphorus are uneaten fish food, fish feces, organic matter (primarily leaves and pollen), etc.
Complete water changes will solve the problem but will create other issues that may be detrimental to the health of the fish and other pond inhabitants. The overall most effective and safest way to control Phosphorus is through the use of a binder such as PhosOut. This product binds the Phosphorus ions together. They then sink to the bottom of the pond where they will remain completely inert until removed.
This is a post from Meyer Jordan regarding string algae. Hope it helps

https://www.gardenpondforum.com/threads/the-algae-never-quits.16872/#post-268683
And here's another link where he talks about string algae

 

[Priscilla]

I had a problem in my pond, I added an aerator, for the fish, not the string algae, within 2 weeks the string algae cleared up.

Mine was pretty bad too. I don't know what that other plant is.

 

[addy1]

Looks like anacharis in your hand, agree with tbendl, that is a good plants. I have read 1 liter of peroxide to 1000 gallons of water to fight string algae. I used it in my arizona pond, it did kill it off.

 

[sissy]

Also if you turn off your pumps and add koi clay it will coat the algae and suffocate it .Water will be cloudy after pumps are turned on but will clear up and koi clay is good for the fish .I now coat my fish food with it because it brings out the color in the fish .You will still need to remove it but it is easier

 

[Tula]

I've had a lot of string algae this year. I think aeration helps , but I'm cleaning the skimmer everyday...just tons of algae. I haven't tried the hydrogen peroxide, but understand it's safe.

 

[teeemkay]

I had a lot of string algae the past month too. I pulled a LOT of it out by hand and then used two doses of an algaecide (Tetra Pond Algae Control) plus got new plants into the water, plus started cleaning the skimmer net twice a day instead of once a day. It all added up and I would say 95% of the algae is gone now. The koi are totally fine, too.

 

[morewater]

It can be killed using D-Solv9 (fish safe) - powder form followed by weekly dosing with D-Solv9 (fish safe) - liquid form.

Aerate it.

Controlling pH is easy using Arm & Hammer baking soda. Impossible to overdose.

 

[johan]

Controlling pH is easy using Arm & Hammer baking soda. Impossible to overdose.

Great tip, thanks.

I'd also like to add that adding some other plant that binds the excess nutrients in your water depriving the string algae is an approach that worked for me - watercress. But certainly not immediate and chems as suggested are probably your fastest solution - they make it sink to the bottom and disappear.

 

[pecan]

Leave the anacharis alone for sure as others have mentioned it is a good oxygenating plant.

Add some air stones and shade sail to keep it shaded all the time and the string algae will die within a few days and not grow back. Shade and oxygen are your friend