Your pond was looking great, but all of a sudden it looks like somebodies poured a bottle of washing up liquid into it, the surface of your pond is is covered in white froth and bubbles, but why did it happen.
There are two possibilities why you have foam in your pond, spawning and protein froth.
This is a common problem and usually appears at the bottom of waterfalls, around fountains or where the water returns to your pond from your filter system.
It’s caused by an excess of proteins in your pond water from dissolved organics compounds (DOC), when water and air from your waterfall/fountain hits your pond it makes bubbles, the proteins get trapped in these bubbles causing the foam effect.
It happens when the organic material that’s produced from fish waste (poo) decaying plant material and uneaten food is broken down so small it gets dissolved into the water (DOC).
It often happens at the start of spring when your pond is getting established after the winter months, but the main reason you have a frothy pond is because it’s either overstocked with fish, you’re overfeeding your fish or you have inadequate filtration and aeration.
What you can do in the short term: You can remove the frothy water from your pond or use a de-foamer treatment to instantly remove the foam in your pond.
What you should do in the long term: If your pond is overstocked with fish try finding new homes for some of them, if you can’t get your fish population down to an acceptable level you will need to increase your filter to cope with the extra load.
Stop overfeeding your fish, only feed your fish what they can consume in a few minutes.
Increase your filtration even if your pond is not overstocked, add plants and increase or add aeration.
Spawning fish can cause your pond to foam, there’s nothing you can do about it and the foam usually goes away in a day or two.