Where oh where has my string algae gone?

[AlyssaFish]

The house I moved into three years ago had what I call a "fountain pond". It's shaped like a slice of pie, in the corner of our yard. It has 3 rock tiers that make up the fountain, and a pool at the base that had 10 goldfish living in it when I got here, and the whole thing was the nastiest pea soup algae.

I turned the fountain tiers into a pseudo bog by adding some large rocks to retain gravel, and putting in some plants. Dwarf horsetail rush. Aquatic forget me not. Golden Alexander. Sedge. A little parrots feather or primrose creeper that I replace each year because it never survives over winter. This got rid of the pea soup algae and replaced it with literal curtains of string algae that would hang from the tiers of the waterfall.

This year, there is hardly any string algae, and the little that there is seems to be growing entirely in the pool part of the pond (seems to like growing on the shells of pond snails!)

This year I have fewer plants than usual (I've been splurging to fill out a new pond), and I have not yet added any submerged plants to the pond. However, there is a much lower bio-load than last year. The first two years I had 17 fish in total in this pond (I do not know the size of the pond of it because of its unusual shape, but I've always estimated 300-400 gallons). I only have 9 in it this year. Is the smaller bio-load the reason that there is no string algae? I have literally had ponds without any fish in them before that have still had string algae, so it's hard for me to believe this is the case!

What do you guys think?

 

[Phaewryn]

From what I have read here in other posts about string algae it comes in the early spring then resolves by summer as plants start to grow back. String algae is normal in the early spring due to the amount of nutrients in the water being greater than the things that consume those nutrients, such as plants, fish, and beneficial bacteria. Did you get started later this year than previous years or not really pay much attention to the pond in the spring? That might explain why you're not seeing string algae, since it's now summer: you just missed it. Or it could be as simple as having less fish than previous years.

 

[AlyssaFish]

I've always had string algae in summer in previous years. Your question made me doubt myself, so I checked through my photos to see how the pond looked last year. Definitely still had string algae by September.

This year I did get some very early on (like in February) due to a couple of warm patches during the winter, but it got cold again and when the water warmed up again the algae never came back!

Perhaps I was just too overstocked last year for the algae to go away like it was supposed to.