How To Calculate Water Filter Size

A bog or wetland filter is the nearly effective pond filter there is.

In this article I volition explain exactly how large or pocket-size to make your bog filter. I will also show my favourite design for a bog or wetland filter.

The bodily size is going to depend on what the ponds main function is.

Ponds crave unlike sized filters for different reasons.

A Fish swimming requires a filter that volition procedure the ammonia the fish produce to keep the water fish safe. This is known as the nitrogen wheel (click the link to read my commodity on the nitrogen bike).

A wild fauna pond doesn't have many fish in it if any. Wild animals ponds such as a frog pond wont fifty-fifty need a super filter.

In this situation the pond itself is the filter. Provided it has a nice residual of plants and surface surface area for adept bacteria.

A water garden swimming fits into the same category as a wildlife pond the amount of waste matter needing processing is so minimal a filter like a bog or wetland is totally unnecessary.

Next we have swim or recreation ponds. Because these ponds are going to have people pond and frolicking in them the water quality needs to be pristine!

So allow's commencement look at the size of a bog filter for a fish pond.

Bog filter size for a fish pond

The size of a bog filter for a fish pond should exist between 10-15% of the area or book of the pond.

For small containerised ponds i like to use the volume measurement.

Book is very easy to calculate on pocket-sized ponds. By and large the volume volition exist stated on the container or preformed pond.

Then equally an example this is i of my wine barrel ponds. The swimming itself is a half wine barrel. This holds about 100 litres (26 Gal) of h2o.

I purchased a 20L (5 gal) container to create the bog. Its a little oversized if you look at the numbers, but keep in heed it isn't filled completely to the top.

So in one case it'south all said and done information technology would be right around the fifteen% mark.

On larger, irregular shaped ponds using surface surface area to summate the size of the bog filter is easier.

If you are unsure how to calculate the area or volume of a pond bank check out my article on calculating pond volume/area.

So if nosotros employ surface expanse to calculate the bog size, nosotros are still aiming for 10-15%

Equally an example a pond with a 40m2 surface area would accept a bog of 4-6m2.

On these larger in-ground i like to have the bog and pond seperate and connected by a stream.

The pump sends water up to the bog filter and so information technology is returned via gravity dorsum into the pond.

Bog filter size for a swim pond

For a swim or recreation pond the bog filter should be 25% or more.

If you create an up flow bog or wetland filter i believe 25% should be sufficient.

When i say "upward menses" i mean that water is pushed up through the rocks, gravel and plant roots.

This is basically a scaled up version of what i created for my vino barrel pond.

I notice up period bog filters more efficient equally the h2o is forced upwardly through all the media that contains the practiced bacteria.

It is the bacteria that are responsible for lxxx% of the cleaning. The plants simply take care of 20%.

There are other designs for bog filters for swim and recreation ponds. They exercise crave a larger area for the actual bog. Generally l-100% of the pond expanse.

I do find these systems interesting. And the fact that they are powered past a simple air pump is only brilliant.

Best bog filter design practices

So like i just mentioned i am a big fan of upward flow bog filters.

Past forcing the h2o up through all the rocks, gravel and found roots nosotros are ensuring that every little flake of water is purified.

If nosotros allow the water to flow down from the summit it volition take the path of least resistance. So what happens is we aren't utilising all of the surface surface area.

Both systems work. I take just plant that i go better results with a smaller footprint when using the upward flow model.

Im also very large on providing an area for solid waste to accumulate.

Over time all the fine materials such as cleaved downward leaves and fish poo form a sludge.

Past allowing that stuff to settle in the filter where we have tons of bacteria information technology greatly reduces maintenance.

On my small bog filters i similar to add a valve that i can open upwardly to articulate out the build up of sludge.

The larger in-ground bog filters its easier to incorporate a make clean out sleeping accommodation.

Depth of the bog filter

Depth is a funny outcome. Some articles will tell yous not to go any deeper than a foot (30cm).

My offset experiment with a bog filter i used an old 220L (44Gal) olive oil barrel. The overall depth was at least 2ft.

It'due south still working great!

One of the things i love almost bog filters is that even if y'all don't go them 100% right, you'll still get fantastic results.

So don't exist overly concerned about the depth. What is more important is getting the water dispersed evenly through the entire bog.

So if you have a large shallow bog filter you demand to create a system of pipes to disperse the water evenly throughout.

This is another surface area where the void space for the solids comes in handy. It allows water to puddle in the bottom of the filter earlier rising evenly through the bog.

Selecting the correct pump or flow rate

For me i want the h2o to take anywhere from 5-x minutes to pass through the bog filter.

The closer to 10 the better.

You demand to keep in listen that a bog is replicating a wetland. In wetlands the water passes through very slowly.

This allows the beneficial bacteria, enzymes and mice-organisms time to smoothen and cleanse the water.

Calculating the period rate of a pump per minute is simply a matter of dividing the menstruum rate stated by sixty.

The all-time way to set it up so you tin can go the flow just correct is past splitting the hose line going into the bog filter and incorporating some flow valves on each branch.

Now you can dial in the period to exactly what you want. The remaining flow can belch back into the swimming as a jet or be added to a stream. It all depends on the pond design.

Sizing the rocks and gravel for the bog filter

On the modest filters i tend to utilise 20mm pebble. Im in Australia and we have a rock called scoria which is my go to in my small filters.

On the larger filters different layers is most effective.

The first grade of stone directly above the solid settling zone are larger rocks. Almost the size of a rock melon.

Adjacent we layer some medium sized rocks nigh the size of a fist.

Lastly we come in with small rock 20-25mm (ane″)

The plants are planted direct into this top layer. Each layer is about 20cm (8″) loftier.

When planting remove all the soil. We want the plants to swallow nutrients from the water itself.

Selecting the right plants

When selecting the plants for your bog filter. Try and cull plants that are active at different times.

Apparently in areas with sever winters this is impossible, so merely focus on plants for the other seasons.

Many people have swell success growing a mix of perennials that are suited to their local environment along side tropicals that they care for equally an annual.

The tropicals abound really fast and strip loads of nutrients from the water during the hottest months.

Considering they cannot survive the winter there is no worry about them condign too invasive.

Speaking of invasive avert annihilation that will take over. Diversity is the cardinal.

Hopefully this has helped you out a footling.

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