We've tried many different systems for removing muck from different kinds of ponds. What we've found is there is no one type of system that works perfectly in all ponds. We've also learned peoples' expectations vary a great deal. One person can love the same vacuum system that another person hates even in the same type of pond.
Tailor a system to your pond and expectations.
What is muck?
Also called mulm, sludge and other things. Muck is everything that settles to the bottom of a pond. Leaves, dead algae, parts of pond plants, fish waste, soil from plant in the pond, soil runoff from surrounding landscape and anything that blows into your pond. All these items are broken down into smaller and smaller material until it's very fine. Basically a compost pile in your pond.
Silt, at least my definition, is the extremely fine matter in muck. Silt is normally defined as clay but I include organic matter that's about size of clay particles or smaller. Single cell algae is about 25 microns when alive, much smaller when dead and decomposing. These particles are so small that water has a difficult time passing through even a thin layer of silt.
Is muck dangerous?
There is no single answer to this question. In a wildlife pond where insects, frogs, birds and a diverse system is desired muck is a key component of the pond. In a Koi pond only water and Koi may be desired. Koi are large animals that can be harmed faster than other creatures when O2 gets low plus the many years of inbreeding Koi have lowered their defenses.
Muck does release harmful gas, use O2 and harbor bacteria. But it's also true Goldfish, Koi and other creatures have always lived in these conditions. It's only in the past few decades a tiny percentage of these fish have been kept in spotless ponds. The key as always been the number and size of fish for a given amount of water and conditions. Certainly muck would lower the number of large fish like Koi a pond could support.
Leaves can be scooped out of a pond with a simple mesh net. As the net is moved water passed through the holes in the net but leaves don't and are trapped. And a net can whole a pile of leaves because water can pass around the leaves and out through the met.
But the fine silt will also pass through the net's mesh. Most people's first thought is to get a fine mesh net which will trap more silt but some will still get through the net. What's more the finer the net the harder it is to push water through because the mesh takes up so much surface area and the holes let so little water through. Removing most silt would require filters in the 5 micron range, so tight water must be under pressure to pass through in reasonable amounts. Since one particle clogs one opening in such a filter they would need to be replaced every few minutes.
The best way to remove silt is to pump it out of the pond along with some water. The problem is leaves, string algae and large items can clog pumps. A pre-filter on a pump can handle some leaves. For ponds with a heavy load of leaves and silt we suggest a 2 step approach. First get out most of the leaves using some net type system. Then, after the water settles, pump water out of the pond from the bottom to remove silt.
If you don't want to lose water when pumping out silt the waste water can be placed into a holding tank. In a few hours most of the silt will settle to the bottom of the holding tank so the top 90% of the water can be returned to the pond. However in most cases it is easier and better to use waste water for garden irrigation and top off the pond with fresh water which performs a water change.
Leaf Rakes on the end of a pole can be dragged along the pond bottom to collect debris. Very cheap, $30 complete, but can take some muscle in ponds with heavy leaf loads. Hard to get "every" leaf because the net stirs the bottom. Good for smaller ponds. Fast setup, easy storage, make these good for daily/weekly maintenance. Limited silt removal.
Venturi vacs collect debris in a fabric bag. $50 to $175, higher price = more power, faster vacuuming. Takes some time to setup but pretty easy to use. Easier to remove all the leaves. None remove silt.
Removing water from the bottom of the pond along with fine silt and some leaves. These systems include:
- Siphons are the cheapest silt vacuums requiring just a length of hose or pipe. In all but the
smallest ponds a pole is needed to get the hose to the bottom which can bring the cost up to the $50 range. Pond must be above grade
or near a lower grade. Can be hard to get a siphon going.
- Shop vacs are most like the household vacuum cleaner. About $100. Removes water and silt
from pond and leaves. Very limited vacuuming time before vacuuming must be stopped and tank emptied. Very limited reach. Most are
not designed for use around ponds and therefore are dangerous
- Water pump, most powerful, $150.
Bottom drains are semi-automatic vacuuming system which work 24/7. Designed to vacuum both large debris and fine silt they're the easiest vacuum to use but most difficult to install properly.