It is no secret that I like a good healthy and biologically-diverse water-body or 5 in any gardenâŠ ohhh so many benefits you’d be mental not to have one!
My most voluminous one is an IBC tank (International Bulk Container) that i’ve converted into an above ground native fish breeding tub. Having an above-ground water body of this kind has several qualities which lend itself to high algae load so i’m going to use this as an example of how to holistically deal with algal bloomsâŠ particularly the annoying but not deadly ‘String’ or ‘Matt’ Algae!
Now, a bit of background; Algae is an immense and extremely diverse group of photosynthesising organismsâŠ often thought of as very simple plants. Particularly focussing on freshwater ponds, you get a range of slimy and short-length algae that cling
to surfaces which are generally beneficial. String Algae is a filamentous type that starts growing to tough fine string lengths of over 7cm and keeps going!!! This can grow very rapidly under the right conditions and double its volume in 24 hrsâŠ not deadly to us but a big inconvenience for small fish and tadpoles who tend to get caught up in it. Plus it can get quite unattractive! It even tied up some Water Lily flower buds and stopped them surfacing this year. HonestlyâŠ I was toying with the idea of drying quantities of it and turning it into baskets or hats or something!!
Conditions that favour rapid algal growth are water warmth, high sun and high water nutrient availability, so any algal problem can be first seen as a response to any or all of these imbalance conditions.
- Water warmth: Ponds that are shallow and of small water volume are often the worst for this as they warm quickly from external factors. It helps to maintain some depth when planning/constructing even small ponds and sheltering away from overly-high sun exposure, particularly during the afternoon.
â This is not a problem for my 800cm deep IBC tank although the vertical depth of its walls means it picks up some extra sun-heated surface area than an in-ground water body. (Am planning on cladding the tank to reduce it’s sun-exposed surface area.)
- High sun: I mentioned Algae is photosynthetic, sun is it’s energy! Meaning if you have a pond or dam with dawn till dusk sun, you’re likely to have a fair bit of algae!
â I’ve situated the IBC tank with a large tree to it’s West. This shades for most of the afternoon but over all a fair bit of sun is received through tank walls. Cladding will help stop light getting through.
- High water-nutrient availability: If you feed fish make sure you don’t over-feed as that feeds the Algae. It also helps to have lots of strong growing aquatic plants which readily take up excess nutrient as it becomes present. I like using things like Duckweed amongst others, as it readily takes dissolved nutrient out of the water, converting it directly to chicken food.
â Speaking of chickens, I believe they have figured out a way to perch on the edge of my IBC to eat KangKong (Water Spinach)âŠ fresh chicken poop may be the excess nutrient load i’m trying to avoid! :-/
While you are getting on top of all of these issues, there are a couple of things you can do that will help decrease the String Algae in your pond or dam… NOTE: Avoid using chemical AlgaecidesâŠ they will kill all of the beneficial algae as well as the targeted stuff, leaving a gap in your food chain and a chance for something nastier to jump in!
It turns out Barley Straw that is submerged in water will be decomposed by a fungus, releasing a compound that blocks the formation of new String Algae. This doesn’t kill the adult strands but seems to definitely reduce or stop it’s baby-making for a period of time. The act of pulling the long strands of adult String Algae out of a pond’s depths suddenly feels like a far more fruitful activity!
A bit of a shortcutâŠ you can buy the Barley Straw Solution in a bottle now from your local garden supply joint. I got some and tried it in the IBC. Seems to work well but this isn’t something to solve the problem completelyâŠ just a handy tool! Of coarse, if you havn’t addressed the roots of the problem then the speed with which the algae bounces back is still rapid.
The systematic approach always wins!!!