Wildlife pond

A quick piece of guidance based on looksee's info. It's the nutrient both in the water and around the pebbles which is allowing the algae to grow. It's held in the water as nitrogen based compounds (such as nitrate and nitrite) and leeches out of decaying plant matter. The largest source in a natural pond (with no fish) is leaf-matter, which breaks up and falls between the pebbles and becomes a sludge; but runoff, atmospheric deposition, and as components of source water are also significant sources. Taking out the leaves is by in far the most effective way of dealing with excess nitrogen in the system.

Washing pebbles is one way to cut it down, but the objective is actually to remove excess organic matter from the base of the pond and only to rinse the pebbles in pond water (not tap water due to the chlorine!) as this will leave the beneficial organic slimes and algae attached to the surface of the pebbles. Those beneficial slimes and algae actually break down nitrates and nitrites by consuming them and out-competing the pea green algae. And don't let the pebbles dry out either as many of those bottom dwelling slimes are anaerobic, meaning that they live and exist in low oxygen environments.

Adding a pump and fountain or waterfall is beneficial too as this creates very active communities of aerobic algae (oxygen dependent), which again out-compete the green algae and work to keep the water clear. Oh - and planting lots of pond plants in suitable pond soil (and not common soil/clay), is another tool to manage green algae. As I said before, various mint plants are good for ponds as they build significant foliage and stems, so they consume the nutrients quite quickly (and can be trimmed back quite easily).

So that's my view on the nitrogen cycle from about 5km high (ie, very simplistic).

Try get the balance right with marginal plant life, then you don't have to worry about external sources too much. Examples here:

https://www.newlands.ie/collections/aquatic-plants-outdoor?srsltid=AfmBOoo8NjVxrKnh-YciE7ieXrD9TtKiGTE9Usq5amDpvsvX7A2ErCCU

This is the pond soil to use:

https://www.newlands.ie/collections/aquatic-plants-outdoor/products/westland-aquatic-planting-potting-mix-litre

Hope it helps!

Ah yes, my misunderstanding. But you are right - they should be washed to take off any limes, salts or dust.

The acidity will be a an unavoidable local occurrence, but at the end of the day that's the natural acidity level, so the specialisation of the local plantlife will reflect that, as should the pond plants! All working in harmony.