How can i keep my garden pond clean?

my water pond keeps getting scummy, what do i need to do to keep it clean and clear.

looking for tips and tricks

Water + Nutrients + Sun = Algae.
Poor water movement = Scum (protein, plant, other)

If you can alter the equation, then the algae can be controlled.

If you have plants in the pond, they will remove a lot of the nutrients.

You can reduce the sun in several ways: Shade over the pond (tree, shade cloth); Floating plants that cover at least 50% of the pond; dye the pond water. Look for a dye that colors the water blue. Looks pretty natural, and cuts out enough of the light that algae needs to really reduce its growth.

You can kill algae spores while they are still drifting in the water with ultra violet. There are UV attachments to add to your pond filter.

If the water circulates well, good pattern, good rate, then the surface scum will get churned into the water and removed by the filter. You need a pump that will circulate the pond water at least 5x per hour for smaller ponds, and at least 1x per hour for very large ponds. This adds oxygen to the water and this helps the decomposer organisms that help to break down pond waste.

At least once a year clean out the pond. Vacuum the worst of the debris off the bottom of the pond.

What size is the pond?
Is it planted?
Are there fish?
What sort of equipment are you running?
Got any pictures?

OK, back from work, I can add to the answer above.

There are many types of ponds, so answering the questions at the end of the last post can help.

If this is a Koi (or Goldfish) pond, then the fish food contributes protein that gets decomposed into ammonia, nitrite and nitrate and other plant nutrients. I am considering algae a plant in this regard.

To remove the nutrients in a pond with goldfish or koi, live plants are the best, but you need to do some things to keep the fish from eating the plants.
If you plant them in a mesh pot, sold for pond plants, and the plant mostly grows out of the water, just the roots in the water, then the fish cannot destroy it. There are a lot of plants that grow this way, some with very showy flowers.
Some plants grow well on the surface, even if the fish nibble the roots. Pistia stratiotes, Eichhornia crassipes are 2 very good plants for this, but are invasive in climates where it barely gets into freezing. See if these are available for you. If the pond surface is shaded (and these plants can do this) then the algae cannot grow very well. The plants are also removing most of the nutrients they need.
You could route the water from the pond through a separate stream where the fish cannot go, but is filled with plants, either in containers or directly in the water. If the volume of this stream is about 1/10 the size of the main pond, and well planted, this seems to be a very good minimum ratio of plants to fish. The water should run slowly through here. This stream should be quite shallow. Plants like lotus, Japanese Iris, many Sedges (caution: some are invasive), Papayrus, Water Canna, and MANY, MANY more plants can be grown like this.
Plants need carbon dioxide, which is in short supply in the water. The best way they can get it is to grow their leaves on the surface or above the surface, in contact with the air. Underwater plants have a struggle to get enough CO2, and are not nearly so effective at removing the nutrients that also feed algae.

If the scum is not algae, then control depends on what it is composed of.
More details can help.

If this is a fountain, not a fish/plant pond. No fish. No plants.
Cleaning it and keeping it clean might be more along the lines of swimming pool maintenance. Use a net to scoop out all possible debris. Keep the filter clean, and use a multi-stage filter that traps leaves and coarse debris as well as finer debris (actually, the same kind of filter as a fish pond would use, just no biological media). Add chlorine such as laundry bleach to kill algae and microorganisms. A larger fountain might have 2 routes for the water: A general circulation pump, and a pump for the spouting fountain part. If this is the style you have, then run them a couple of times per day. The spouting, splashing one breaks the surface so and dust or other debris that lands on the surface gets churned up and then removed by the filter. This only needs to run as long as needed to keep the surface clean. The circulation pump will keep on circulating the water in the main basin, and keep running it through the filter, to keep it clean. This one needs to run for a longer time.

The way we keep the ponds clear here in UK is, at the garden centres where you can buy WATER plants strictly for ponds, you plant them in Plastic baskets that are woven to resemble wire work, You can then place a liner from old sack cloth like you were lining a cake tin, then add special compost that is already mixed for pond plants, plant up the basket and add a 1 inch layer of pea gravel to weigh down the soil AND prevent the fish (if any) nibbling the roots.
To help prevent murky or cloudy water and thus helping the green Algae to form and spread. you can purchase specially made STRAW bales, these are small square bales of straw that are tied , place onto a long cane, then put them into the pond, mid way, they will get soaked, but still float collecting the Algae, whatever is the natural ingredient of the straw, this prevents the build up of more algae.

You need the change the straw bales every month or so BUT only in the months when the ALGAE is at it more problem stage.
There are NO chemicals in the bales, it is the straw that releases some gas or whatever and prevents the Algae from forming.

Hope this helps you out as it is by far the easiest, most cost affective and most harmless way to go in my opinion.

Kindest Regards.
WeeNel.