Pond Care Page Two
Last Updated: 11/22/06
This page covers various issues and questions that I have received recently.
Magically Appearing Fish
Dirt Ending up in Ponds - runoff and spilt plant pots
Other mystifying aspects of ponding are covered on other pages on my site. For example, on my
health question page, I have answers to "Where did my fish go?,"
"Why did my fish die?," and "Why is my fish bent?" among other things. On my water chemistry page is a section on dealing with pond poisonings
I have often got the question, "I found a [fill in the blank] fish in my pond but I didn't add that
kind of fish. How did it get there?" Here are some possibilities.
- The fish were added to the pond as eggs or fry attached to some live plants that were added
to the pond.
- A person, unbeknownst to you, added the fish to your pond.
- The fish ended up in your pond during flooding that washed them into the pond.
- The fish came to your pond as fish eggs that were attached to the legs of animals that visited
another pond before yours where they picked up the eggs. For example, eggs may stick to the
legs, fur, and feathers of herons, raccoons, and most mammals and birds. This is pretty
- A predatory bird had a fish in its mouth from another pond and accidently dropped it in your
- Sometimes fish change appearance over time so that a fish that you added a few years back
may look like a new species or individual when it is not. Goldfish change color throughout their
lives and koi to a lesser extent.
Sometimes liners may shift, float up, collapse, or otherwise cause headaches. If the liner is new,
and the pond is not yet full of water, simply adding water may force the liner into position. The
weight of water holds most liners down. If a full pond has a liner that floats up, there are a
number of things to consider.
First, is there water or air under the liner. If it's air, then you may need to lower the pond level
and slowly push the air along so you can work it out from under the liner. Most air is squeezed
out when a pond is filled with water. If the liner is floating up because of water, you have to
consider the causes. Here are some possibilities.
- 1. Cause - a high water table. If the water table is high, then water pressure from underneath
the liner will push up on the liner. Sometimes, the water table is only high after a heavy rain or
flooding. In some areas (low altitudes), the water table may always be high.
- 1A. Solution for temporary high water tables due to flooding:
The water needs to be drained from under the pond. If this happens every time it rains, a
drainage system can be built under the pond. Pull out the liner. Pump out the water with a sump
pump or vacuum it up with a wet/dry vacuum. Dig trenches. Lay in PVC piping with holes in it.
Run the piping out to a level lower than the pond. Fill in the rest of the trench with pea gravel.
Put the liner base and liner back into the pond. This will hopefully run the water away from the
- 1B. Solution for permanently high water table:
I am afraid in this case, if when you did a hole, it always fills with water, you really cannot dig a
pond down into the water table. As an alternative, you can build an above ground or mostly
above ground pond. These can be build with wood or cinder block supports that are covered in a
protective fabric or something and then the liner.
- 2. Cause - Water coming from a source other than the ground.
- 2. Solution -
You need to find out where the water is coming from if it is not coming from the earth or rain
itself. It might come from broken water or sprinkler system pipes.
Most of us will have some dirt and associated debris and chemicals entering out ponds after a
heavy rain. A little bit of dirt flushed into a pond usually does little harm. A lot can make the
pond very cloudy or bring with it a toxic brew of pesticides, herbicides, oils, etc. from neighbor's
yards, farms, and so on.
Dirt normally enters a pond when it rains. Here are some ways to prevent and treat that.
- Construct the pond on high ground, not in a low area of the yard if at all possible.
- Raise the rim of the pond a few inches above the surrounding ground.
- If you have an uphill neighbor, try to impress upon them how important it is to have
stormwater management in effect (where the water will go) as well as how important it is to not
flush toxins downstream (to your pond and natural waters). That means that you do not want to
use fertilizers (cause algae blooms), pesticides (kill fish), herbicides (kill plants), petroleum
products (oil and gas), etc. where they might run into your pond or natural waters.
- If the pond must be at a lower grade, then build a drainage system. This entails digging a
trench at the higher end of the pond parallel to the pond. Dig down a foot or two in most cases.
Line the bottom with gravel. Then, put in PVC pipes with holes on the top. Top off with more
gravel and then sod or more rocks (rocks work better but may not look right). Run the pipes
around the pond and downhill. When rain and runoff come towards the pond, they will go down
through the rocks, into the pipe, and then downhill away from your pond.
- If you have a drain spout that will accumulate water above the pond or run into the pond,
attach piping to the spout and run piping down below the pond. We have that on one of our drain
spouts. Without it, water would pool above my pond. It still does some as some water runs up
and over the gutters.
- For small muddy areas at the high end of the pond, you can remove the dirt there and replace
it with liner. Lift up the main liner if possible to a higher level as well. With my 1800 gallon
pond, one spot seemed to run in more dirt than elsewhere so we removed the dirt, lined it with an
extra piece of liner, and put in more rocks over the liner. It seemed to help.
- Check around the edge of the pond for where most of the dirt is coming from. The liner can
be raised there or other diversions put into place to run the dirt away from the pond instead.
- Increase filtration, adding finer filtering materials. Squirt them off regularly to help collect
- If chemicals are added along with the dirt, put some fresh, activated carbon in a mesh bag in
the filter to help remove those chemicals. Change the carbon in a few days with new carbon until
the problem passes.
- Dirt will normally naturally settle over time. At the same time, water movement is needed
for filtration and oxygenation so it will take longer with water movement for dirt to settle. Once
settled, dirt can be removed by electric pond vacuums (will not work with venturi pond vacuums
which use in-pond filter socks that dirt goes right through) or wet/dry shop vacuums (the pond
level must be low to use that kind of vacuum).
- A quick and temporary fix for water cloudy due to dirt/soil is to add AccuClear by Aquarium
Pharmaceuticals or other such polymeric coagulants. This will cause the dirt to clump and sink
or be sucked into the filter. Be sure to maintain good aeration while using it as it does lower the
oxygen usage abilities of fish.
- Work on the pond to prevent future problems (see prevention above).
Dirt Entering a Pond from Other Sources:
Dirt may also end up in the pond when dirt/soil is used to plant up aquatic plants. Such pots can
easily be tipped over by various animals in the pond. Raccoons love to knock over pots in my
pond. Pots should be topped with pea gravel to prevent dirt entering the pond by fish rooting in
the pots. If the pots are knocked over, the gravel may end up in the pond anyway. Heavier pots
are less likely to fall over. If animals cannot be prevented from knocking over plant pots,
consider potting with 100% pea gravel or using commercial aquatic plant soil which is a brown
cat-litter like soil that makes less of a mess and will not cloud the water very much when spilt. It
does not secure the plant as well though so when the raccoons knock over such pots in my pond,
the plants are usually floating around free. Treatment for dirt from pots is the same as from
runoff listed above.