One of the most misunderstood happenings every year in the life of pond keepers is the spring PEA SOUP. The cries for “Oh my God, my pond is green!” echo throughout the land – somewhat akin to the age old cries of “the plague, the plague”. However, a little understanding, a splash of education and maybe it “t’aint” so bad after all”.
The winder pond is very much like a refrigerator. It stores up all kinds of leftovers and organic stuff (leaves, fish droppings, dead things, etc). The food in the refrigerator doesn’t really rot too badly, too quickly, but when we pull its plug and leave the door open for the spring-clean out- WATCH OUT!. All of the leftovers have had time to age. Now they process into other forms -very rapidly. The stuff in the pond has also had time to prepare to process.
A lot of it has converted from ammonia to nitrites to nitrates already and the rest is ready to convert very quickly. But these nitrates (read nitrogen fertilizer) have had nowhere to go. The plants have been asleep in the winter chill and have not been able to convert them to plant stuff( the plants, remember, eat the nitrogen through their roots and convert it into more plant cells to make the plant bigger. In other words, the plants take the fertilizer out of the water and purify the water. Remember, the plant may be “in” the water but the fertilizer itself is no longer in the water: it is in the plant, which is only surrounded by the water)
When Mother Nature hits the pond with a good warm sunny day, the water warms up enough to allow algae to grow. and it does. After all, the pond is full of nitrogen fertilizer (read “algae food”). So the algae starts growing geometrically – that is, for example, each day it might double in quantity as it eats, grows, and reproduces. you look in horror at it like it’s the Blob come to eat your pond.
But, and here’s where it gets interesting, it is saving your pond. Remember all of that nitrate that had built up all winter? Well, the algae is there to balance the pond and get rid of that potentially deadly nitrate by converting it to safe algae. So, the smart pond keeper encourages the Pea Soup to grow as fast as it can, to convert all of winter’s chemical buildup into little obnoxious and yucky plants just as fast as it can. Meanwhile, the pond keeper needs to start housekeeping and clean the pond of all of the larger stuff-leaves, sticks, etc., from the pond’s bottom with his or her skimmer net. Then “Poof”, one day after a week or two, the pond is clear as a bell. Now you, the pond keeper, have to act to do your part. The pond is clear only because the algae have converted all, repeat all, of the nitrates to algae. Then they run out of food – no more nasty nitrates – and all of the algae died of starvation – all at the same time. “Poof”. The pond keeper now has to quickly take his/her siphon hose, vacuum, whatever, and do a 20% water change OFF OF THE BOTTOM
What you have just accomplished is that you have chemically cleaned the pond water of all of the winter build up. You no have a pond with its normal stability, buffering, hardness, aging, etc., but with no nitrate.
In a week or two the weather will allow the regular pond plants to start growing and they will continue the job of removing the nitrate as it is produced. There will be no more pea soup in a balanced pond for the rest of the year.
“Ahhhhh, clear water, with no more work!”