I have a water garden and I just moved in, I found a mesh sack of black rocks. any idea what these are for?

Question

The sack was at the bottom of the pond (which is about 3-4 feet) and it is definitly not for decoration

Answer 1

It might be activated charcoal to help with water clarity.
You should consult your local nursery to be sure, and for any tips on maintaining your water garden.

Answer 2

It is to keep your water feature from looking "murky" or cloudy.... as they sometimes turn a rather unnatractive brown muddy-like colour! (or they get overthrown with algae)! Perfect ponds are always crystal clear, but in reality - they are seldom so! - It's so hard to keep the water looking clean and fresh. We have a large pond in our garden, and what we tried recently is put a fountain in it... it was pretty opaque before, and now, just a few weeks later - you can see right to the bottom (I'd say it's about 8ft deep).
Don't really know what your water garden is like - maybe this will help you in the future!
Another cheaper (well, saves on hydro!) alternative is to put bundles of Hay in your water.... something we picked up when we lived in England and had a little pond at the side of the house. (might look a little odd though....so try to disguise it or have it hidden under water).

Answer 3

Bags of gravel are sometimes used as growing media for beneficial bacteria which provide organic filtering of the pond water. I have them inside a skimmer in my pond, also contained in a mesh bag of gravel. You can order a new suppl of the bacteria online or get some at a local nursery which carries pond supplies.
It's easier to balance a pond organically with bacteria and water plants then to keep dosing it with clorox or such to keep down algae. You may want to get some water gardening books to read from your local library, as an untended pond can quickly turn into a mess.
Check the links for info and supplies:

Answer 4

It's probably carbon for water clarity. You don't say how big the "rocks" are, but carbon (aka activated charcoal) is usually quite small, more like gravel size. Carbon only works for a short time and must be replaced on a regular basis, so if that's what it is, chances are it's old and you can discard it and replace with fresh stuff anyways.

Answer 5

Decoration for the bottom of the water garden!

Answer 6

I agree with many of the answers here... It is probably charcoal. Charcoal is used to keep water clean and acts to filtrate impurities in the water. If you use a water filter on your sink, like a Brita, inside the filtration piece is charcoal which is used to purify the water. That's why you had charcoal in your water garden.

Answer 7

You are lucky that you got these rocks collected for you! My dad and stepmom walk along the beach to collect rocks to decorate their backyard and fountains. If the ones that were left behind look nice it will save you a lot of time looking for nice rocks.

Answer 8

Holding potted plants down in the water......or a submersible filter for the water pump system.

Answer 9

This could be for securing water potted plants to the place you want them placed in the water, otherwise I would have to suggest they are for decoration.

I'm adding -- moments later -- on valuable information given to me in Y!A from Patz.. a link to building a water garden.
http://clearwaterlandscapes.com/pondebook.htm
I hope this is helpful with your venture in maintenance.

Answer 10

Its for the edge of the pond, gives it a "real" pond look.