You finally have your pond in your garden and have been told that maintenance is almost nonexistent. You are right, but there are some pond disasters that do happen. To recognize them and be able to deal with them is easy, so don't panic.
Most pond disasters are easily fixable, so let's start with the most common and easiest to deal with.
My pond has turned to green pea soup!
The pond has turned to green pea soup and you have only had it a few days. First, don't worry, this is a common problem and an easy fix. Second, do not empty the pond and start over again. You will face the same problem again in a few days. The pond turns green because it is not ecologically balanced. When sun hits water, algae grow. This will never change. Your bird bath gets green, your swimming pool gets green, lakes turn green. So we must balance the pond to keep the algae from growing.
If your pond water turns green, have a look at it and decide if the water has suspended microscopic particles of algae in it or if there is something floating around in there that looks like angel hair spaghetti. You will have no problem seeing the difference.
If the water is green from microscopic suspended algae, here's why: If sun hits water, algae grow. If we want the algae to be filtered out, we can do it easily and ecologically. Figure out the square footage of your pond (length times width) and add one bunch of anacharis (submerged vegetation) per square foot of surface area. The anacharis filters out algae. It also is an oxygenator, so fish can breathe, and it is great goldfish food. Don't worry because it grows faster than goldfish can eat it. You have now solved most of your algae problems.
Next, cover about 1/2 of the surface area with floating plants. That will keep half of the pond in the shade, which will keep the water cooler, the fish happier and the sun from being so brutal. Floating plants could be water hyacinths (illegal in some states, so check with your local nursery), water clover, parrots feather, water lilies or any of the other floating plants.
You now have a balanced ecosystem that will keep itself clear with no help from you as long as you don't have koi or feed goldfish.
My pond is leaking!
Another easily fixable disaster is a waterfall leak. I get calls all the time saying, "My pond is leaking." Most of the time, I say, "No, it isn't," and then explain that most likely the reason the water level is falling is because water is leaking from the back or sides of the waterfall.
Turn off the waterfall pump. Fill the pond up with water. Don't forget the dechlorinator. Leave it for 24 hours. Tomorrow, see if the water level is where you left it. Look at that, it is! So now you know that water is somehow leaking out the back or sides of the waterfall. Turn the pump on. Have a look around the waterfall. Most of the time you will find the leak immediately because you can see it. Tip the rocks or move the hoses toward the pond so all the water returns to the pond, and your leak problems are over. Occasionally water is splashing out, so check for that as well. If you have statuary, make sure there is not a strong wind blowing and that water from the spitting statuary is not being blown out. Also, if the statue is on the side of your pond, check it to make sure water is not dripping down the side or front of the statue and out of the pond.
If you are using a weir or biofalls for a waterfall, check the edges. Sometimes the water can hit a rock and splash out; other times the biofilter box can move around and the seal between the box and the liner can fail.
Water is splashing out!
When dealing with splashing water, remember this: Water cannot fall more than one half the width of what it is falling into without splashing. If the area the water is falling into is four inches across, the water will splash if it falls from more than two feet. This is universal and can be difficult to overcome. You can make the falls lower, you can make the width wider. But if you have purchased a wall fountain or a three-tier fountain and put it in a small area, resign yourself to refilling your pond often.
Mosquito fish are a great natural solution to the problem of landscape pond insects, but you'll need to take some steps to keep your fish healthy.
Pond leaks are not fun. Noticing a water level drop, you are sure you face repairing your pond liner. Before you panic, make absolutely sure it is a leaking liner and not another problem.