Duckweed in a Pond

Duckweed has featured at the Chelsea Flower Show in the past, but this doesn't mean it's desirable to everyone, nor does it mean it's easy to look after. 

When duckweed starts to thrive it will literally cover the entire surface of your pond if left untamed. Eventually your pond could look like the image, which almost looks like a surface you could walk on. (Once when walking the dog, she thought it was a solid surface, and did she get a suprise!)

Some fish will eat duckweed, but not at a fast enough rate to hold it back.

Duckweed is not necessarily dangerous to your pond, it will make your fish and wildlife difficult to observe. Dead and brown duckweed though, should be removed from the pond as soon as possible, as it can sink to the bottom of the pond and pollute  the water.

The ideal solution to get rid of duckweed is to use a pond skimmer, a pond skimmer works by "skimming" the surface of your pond and removing any excess waste, this includes duckweed.

There are difficult types of skimmer available, you can buy stand-alone skimmers, which have their own pump built in and will float around the pond. You can also buy a skimmer which will fit onto your pump, sending the debris to your filter, but please note, your pump must have a sucking option for this to work.

To begin with, we'd advise to remove as much of the duckweed as possible yourself by hand, then to add the skimmer, this will prevent the skimmer from clogging up too fast and means it will work more efficiently, hopefully preventing it from growing back.

Stopping Blanket Weed

There's no doubt that blanket weed sometimes know as string algae is unsightly, and can not only spoil the look of your pond, it can also cause many other problems too.Blanket weed is easily recognisable as a hair like structure which will grow from the sides of your pond and other surfaces in the pond itself, it thrives off sunlight, oxygen and fresh water, which is why you should never refill your pond like some people do, it sounds like the logical thing to do, but it's like feeding the fire.

If you want to stop blanket weed, then there are various forms of removing it from your pond, I will list these below, with a short description of how they work:

Powder Chemicals - You would normally sprinkle these into the water around the edges of your pond, these are designed to kill the blanket weed at it's root, which is the sides of the pond normally. 
Pros: works fast and effectively, ideal if you're rushing to get rid of it for a weekend BBQ or something. 
Cons: The dead blanket weed will sink to the bottom of your pond, and if not removed effectively will pollute the pond.

Example of a Natural Enzyme

Liquid Chemicals - These are a very simple to use solution, which you would dose the correct amount in relation to your pond size, pour it into the pond and let it do the work. 
Pros: rapidly works and effective too, again ideal if you're in a rush.  
Cons: This again kills the blanket weed and it will sink to the bottom of the pond causing pollution if not removed.

Natural Enzymes - These treatments work slowly to remove the blanket weed, normally taking around 2 weeks or so to work. They will remain in your pond breaking down the blanket weed in the future.

Pros: Will not take oxygen out of the pond and hard to overdose the pond. 
Cons: Can take longer to work.

Barley Straw - Barley straw bales can be purchased and put in your pond, they will need to be somewhere with moving water. 
Pros: Completely natural, and works long term (usually up to 6 months). 
Cons: Not ideal in ponds with no moving water, not guaranteed to work.

So which one should I use?  

An example of a powder chemical

Choosing depends on your situation really, if you've got guests coming over on the weekend and you need something to kill the blanketweed ASAP, then a chemical (powdered normally work faster) is probably your best solution as they are faster working. Just make sure to use some type of sludge buster to  consume the dead remains afterwards.

On the other hand if you don't mind how long it takes and you don't want to use chemicals, then maybe barley straw is your best option, just bear in mind that it will need to be placed under or near moving water to be effective so if that's not an option go for the natural enzymes which will break down and consume the blanket weed naturally and continue to over the next few months.

Just be careful when purchasing the powder chemicals, some of the older types which are no longer available usually would kill all plant life in your pond including lilies. These are still on sale in some shops which have got old stock, but normally a fully trained member of staff will let you know. This type is best used in ponds with no plants!