Underwater Waterfall for Your Freshwater Fish Aquarium

Well, if your fish aren’t entertaining you enough, how about installing an underwater waterfall as part of your freshwater fish aquarium  tank decor?

The water isn’t really water, it’s sand and the system uses an air pump to push water up a tube and the water sucks up the sand.

Here is a Youtube Video showing the effect

And all the instructions are available at the  “Instructables Site” Dragon Tamer 458</a> Thanks for sharing Dragon Tamer Number 458…

And here is another example…

And a video showing how to do it…



Fish Tank Ornaments for Fresh Water Aquariums

Fish tank ornaments and surroundings that my tropical fresh water aquarium fish will live in every day will be suitable for their physical and mental well-being, not so much that they match the room colour scheme.

That means – real plants and no unnatural fish tank decorations like coloured gravel.

Fish tank ornaments for tropical fresh water aquariums are divided into three separate sections, the substrate, the backdrop and the internal furnishings.

Fish Tank Ornaments: Substrate

This is the material covering the bottom of the fish tank.
Usually non-toxic gravel or sand. It is used to cover under gravel filters, for bedding plants and covering up the bare glass bottom of the tank.

Many fish like to move the substrate as part of their feeding behaviour and foreplay when about to breed. So, I need to make sure the sand or gravel has no sharp edges. Also true if some of my fish rest on the bottom or have sensitive barbels that can be damaged easily.

Also I need to consider the affects of the substrate material on the water chemistry. Hardness-free gravel or sand for soft water biotopes. Non-toxic gravel or sand for hard water aquariums.

Coral or limestone chips will affect the pH level.

Fish Tank Ornaments: Backdrop


The backdrop  is the solid vertical background against which the internal furnishings are displayed.

For sure it is unnatural to have bare glass on all four sides of the aquarium. I wouldn’t like to live in a glass house.

Most freshwater aquarium fish live close to the edge of the river or lake in their natural habitat. Not often do they stray out into the open spaces of the main stream. So the freshwater fish aquarium decor should simulate an area of the river or lake that is close to the edge.

I can use specially designed backdrops made from plastic simulating plants, rocks and gravel, attached to the outside of the aquarium. Or, paint the outside of the rear wall a dark colour or stick on cork tiles.

On the inside maybe large flat pieces of slate can be positioned against the back wall.

Fish Tank Ornaments : Internal Furnishings

Hard Decor

Water chemistry is the number one consideration when I select the hard decor – rocks and wood.

For rocks in freshwater fish tanks I will use inert materials like granite, slate and gneisses.

Also I need to think ‘BIG’. A collection of large rocks will be more pleasing and provide more nooks and crannies than a pile of small pebbles.

Bogwood seems to be the popular wood used as fish tank furniture. But the tannin in the wood can turn the colour of the water brown.

Whatever wood is used I will need to condition it before installation. Conditioning is usually done by immersing the wood in water for several months. Maybe this time can be shortened by boiling the water and soaking the wood in hot water.


A porous lightweight calcareous rock suitable for hard water freshwater aquariums. Tufa rock can be built up into extensive aquatic rockeries.

Not suitable for soft water fish tanks because of its affects on water chemistry – hardness and pH levels.


A man-made by product of the smelting industry. Lightweight, porous and completely inert.



Heavy and mostly inert. Well suited as a surface for fish spawning.


Broken clay pots and pipes provide interesting shapes and hideaways. Make sure the pieces are clean and do not carry any horticultural chemicals and residues.

(Gneisses : a common and widely distributed type of rock formed by high-grade regional metamorphic processes from pre-existing formations that were originally either igneous or sedimentary rocks. It is often foliated (composed of layers of sheet-like planar structures) : Wikipedia – What !!?? ;[


To be avoided at all costs. Toxic…
Soft Decor
Again water chemistry is a major consideration when I select plants for freshwater fish tanks.

Fish Tank Ornaments: Plants

Aquarium Plants are living things and sometimes more difficult to keep alive than the fish. I need to handle them with care and don’t buy until I’m are ready to install.


Its best to buy plants that have been grown in special tanks. Plants grown in tanks containing fish may carry disease and should be quarantined before introducing them into your aquarium.

Major consideration – Snails. Look out for snails as well when selecting your plants. Make sure no snails end up in my aquarium.

Common freshwater fish aquarium plants include:

Willowleaf (Hygrophila sp)
Acorus variegatus
Aquatic moss
Java fern ( Microsorium pteropus)
Elodea densa (pond weed)
Hemigraphis Colorata (Broadleaf)

So, that takes care of all the separate parts, next up is the setting up…


Fresh Water Aquarium Accessories

OK, so now I’m getting into the meat and potatoes of freshwater aquarium fish keeping – figuring out what aquarium accessories I need.

And the paramount consideration – only use aquarium accessories designed specifically for fish tanks and fish keeping. This way I will avoid any contamination or poisoning of the water.

Fish Tanks

Most fresh water fish tanks are made by sticking sheets of glass together using a silicone sealant. This limits the shape of the fish tank somewhat.

However, glass rectangular fish tanks are easy to install and available off-the-shelf in many standard sizes.

Modern fish tanks are also moulded from clear acrylic. This for sure expands the size and shape options but there are practical considerations.

Acrylic fish tanks are also more durable, lighter and very much stronger than similar sized glass fish tanks
Acrylic aquariums are easy to scratch and because of the refractive index of acrylic there may be more distortion of the interior which will distract from the viewing pleasure.

Price: Check on Amazon

Tall multi-faceted towers are made more for the novelty value and room decoration rather than as a suitable habitat for fresh water fish. These vertical fish tanks provide a small surface area for the all-important oxygenation of the water and allows little lateral movement for the fish. The fish can move up and down but not many fish do that in their natural environment.

Size Matters

I have a conundrum here. I know what fish I want to keep, but I do not have the space to place the fish tank. So do I install the biggest tank I can, and fill it with the fish I want to keep hoping everything will work out OK?

I don’t think so.

I will need to make a compromise on the type and number of fish species I can accommodate in the biggest fish tank I can accommodate.

Some interesting fact:

A large volume of water is easier to keep biologically stabilised than a small volume of water and therefore can accommodate more fish
A large tank is more versatile if I change my mind in the future. A large tank can be compartmentalised by inserting glass dividers
On the other hand water is heavy.
The bigger the fish tank, the heavier the installation will be. So I need to make sure the supporting structure is strong enough. A shelf, a cabinet, a floor standing frame, the floor itself.

One litre of water weighs 1 kgm
One litre is 1,000 cu cm.

In old money:

One cubic foot of water equals 6.23 gallons (UK)
One gallon of water weighs 10 lbs.
So a small fish tank 600mm X 300mm X 300mm. Or, 24 inches X 12 inches X 12 inches weighs approximately 54 kgm or 124 lb

And a large fish tank 1,800 mm X 600mm X 600mm. Or, 6 ft X 2 ft X 2 ft is 12 times the capacity and nearly weighs a staggering 680 kgm or 1,500 lbs

Shape Matters

Deep freshwater fish aquariums look good and fit into many rooms.
However depth is less important than maximising the water surface area for proper oxygenation of the fish tank water.

I don’t have long arms, so a deep fish tank is going to be more difficult to maintain. Keeping the substrate tidy, planting plants and fish tank decorations.

And aquarium accessories, like live plants growing in the bottom substrate will require a huge light on the top to make them grow.
So, a maximum depth of around 40mm to 45 mm seems to be the most practical.

Location Matters

My freshwater fish aquarium needs to be located:

where it is easily visible but away from through traffic to avoid any accidents.
Near an electrical outlet
Not secluded or the fish will become introverts.
In natural light but not direct sunlight.
And at a height where it can be comfortably viewed.
The fish tank needs to be sat on top of 13mm thick styrofoam to take care of any unevenness of the base. And the styrofoam is usually fitted on top of a sheet of 13mm thick marine grade plywood.

Fish Tank Hoods and Cover Glass

The purpose of the hood aquarium accessories is to keep the fish in the tank and to keep foreign matter out of the tank. Modern hoods also contain fluorescent lighting tubes and a controller.

The purpose of the cover glass aquarium accessories is primarily to stop water evaporation. Water will condense on the underside of the glass and drip back into the fish tank.

Some hoods come complete with integrated cover glass but these may be a little inconvenient unless there is some facility to access the fish tank to feed the fish and for the regular partial water changes.

Water Heating

I intend to keep tropical fresh water fish so for sure I will need to maintain the water temperature above the ambient temperature in the middle of a winter’s night when the central heating is off.

And to maintain the temperature within one or two degrees I will need a thermostat as well as a heater.

I could get separate aquarium accessories but seems the most convenient and not so expensive is a combined heater thermostat unit.

And the recommendation is to install two smaller wattage units rather than one large wattage unit. It’s very unlikely that both units will fail at the same time so there will be some form of heating available at all times.

And I should not forget the thermometer.

Thermometer aquarium accessories are cheap so I will buy more than one. And they are also very inaccurate so I will need to check the accuracy against some standard device somehow.

Aquarium Accessories: Filters, Pumps and Filter Media

Filter selection needs to take into account:

Size of tank
Number and fish species
But I need to make sure I don’t instal a pump that is too powerful. Or the fish will be swimming upstream 24/7.

An under gravel filter is a good starting point. If inadequate it can be supplemented by a ‘Hang-on’ filter.

There is also a fine balance between the amount of filter media and the amount of waste generated by the fish.
And if I get it right maybe cheap media like filter floss or foam will be adequate for a ‘Hang-on’ filter.

Water Pump

The water pump is more than a aquarium accessory and is used to move water around the tank and I need to make sure it’s the right flow rate for the size of the aquarium.

Length(in meters) X Width(in meters) X Depth of water(in meters) X 1000 = number of liters of water.

Air Pump

An air pump is essential for adequate oxygenation of the water. Air pumps help with moving the water, limiting algae growth and helping keep the fish in good health.


Filters are used to remove waste from the water so that the water is clean and clear.

Filter Media

Peat or foam is used to remove solid waste and ceramic rings, activated carbon and ‘bio balls’ are used to generate good bacteria to overcome the bad bacteria

Aquarium Accessories: Lighting

Fluorescent lights are the most common type of lighting for freshwater fish aquariums.
Fluorescent lighting systems aquarium accessories include the controller and one or more tubes.
Various tubes are available that emit different colour of light or more technical they emit light of different frequencies.
Probably best to use two tubes. Each tube emitting light of a different frequency so the whole visible light spectrum is covered.

I need to make sure there is enough light to encourage growth of any real plants I include in the tank and to show off my fish and the biotrobe they’re in but not too bright that the fish need shades.

And also remember that some fish naturally live near the surface of the water and expect bright light but others live in the shade, in the rocks beneath the plants and glaring lights can and will damage the eyes of sensitive fish.

Maybe in my freshwater fish tank, if I only add artificial plants, I only need one fluorescent tube the length of the tank. I am told that the fish will swim actively in moderate light and the moderate light will show of the colours of the fish much better.

In the future when I start to grow plants in the tank along with the fish I will need to add additional lighting. So probably the best is to use one long tube the whole length of the tank and another half the size at one end. And I design the habitat so that all plants are at the brightly lit end with shade for the fish when they do venture there.

Test Kits

I will need to test the water hardness, the pH level and the amount of ammonia nitrite and nitrate.
Salt water kits do not work for fresh water so make sure to buy the right kit.

Water Chemistry Adjusters

To be on the safe side let’s also include some chemicals to fine tune the water chemistry.
For freshwater fish aquariums I can use Epsom Salts (magnesium sulphate) and Sodium Bicarbonate.

In the next post I will open the discussion on aquarium decorations.


Choosing Freshwater Aquarium Fish

“Let’s talk about fish, baby…”

The size of my tropical freshwater aquarium fish is pretty much dictated by the location and the space available.
But more about that later.
For now I have a rough idea of the size so I need to consider what freshwater aquarium fish I can keep.

Too many things to consider.

What do I want? More importantly what do the freshwater aquarium fish want?

My wants:

The installation needs to be:

  • Interesting
  • Soothing
  • Easy to maintain

The freshwater aquarium fish want:

  • The water chemistry needs to be right
  • The water quality needs to be right
  • The environment needs to be right
  • My companions need to be compatible

I’ve already discussed the water chemistry and quality.

The environment needs to replicate the conditions the fish would live in if they were free and wild.
I need to consider the type of substrate, whether the fish prefer rocky terrain or one with many plants.

Do the fish seek shelter?

And what fish can live together in a relatively confined space: Are they slow moving? Skittish? Do they eat the plants? Do they eat each other? Are they aggressive?

General Community Aquarium

A General Community Aquarium is a basic set up.
The fish in a general community aquarium can survive in a variety of conditions:

  • Variations in water chemistry
  • Tolerant of occasional mishaps in water quality
  • Not too fussed with the decor
  • Will eat any synthetic fish food

But there is still the big questions – are the fish suitable? Are they compatible?

Tropical Freshwater Fish Size

Are the fish fully grown or will they outgrow the tank?
Can the little fish swim together with the large fish without accidental injury
Can the little fish swim together with the large fish without getting eaten?


Are the fish omnivores (will eat animals) or piscivores (will eat only fish)
Are the fish ‘fin-nippers’, taking chunks out of the fins of other fish. Do the other fish have long fins??


Do the fish originate from turbulent waters or slow moving less agitated waters?
Fish from turbulent waters could possibly survive in well oxygenated calm water but sail-finned species evolved to glide through calm waters will not make it in a strong current.

Tropical freshwater fish from the rainforest will use vegetation to shelter. There will be roots and dead branches to hide in.
Mangrove swamps are similar to the rainforest except the water chemistry is much different.
Fish from the rapids live in crevices in the rocks and under boulders. Not much vegetation here.

Providing enough cover of the right size and shape is very important especially for the small fish who are at the bottom of the food chain and will be stressed out if they have nowhere to run and hide.

Dietary Considerations

Fish with special food needs are better avoided for the moment.
Worms and mosquito larvae may not be available and feeding live fish to a piscivore may be distasteful.
Herbivores may not eat the small fry but will decimate my underwater garden.

Size Matters

Tropical freshwater fish living in an aquarium is not natural for the fish so I need to make it as pleasant as possible for them. The biggest constraint is the size of the tank versus the size of the fish in it.

Some species need privacy. And they may fight for the right.

Territorial species need to have enough space for themselves with enough room in the tank for their neighbours.

Many species enjoy the safety in numbers provided by a shoal so keeping just one or two of this fish type is also destined for failure.

The number and size of fish that a freshwater fish aquarium can accommodate is calculated by the total length of all the fish relative to the surface area of the aquarium.

And its all about the oxygen availability at the surface of the water.

For tropical freshwater fish I need to allow 200 sq cm of surface area for each 2.5 cm of fish.


  • What fish would I like to keep
  • How big do these fish grow
  • Do I have enough space to fit the aquarium in
  • Can I provide the right water chemistry
  • Do the fish eat plants
  • Will they vandalise the decor
  • What decor do these fish need
  • Will the different species live happily together
  • How many and what species can I accommodate in my size of fish tank
  • Can I afford to feed them (Any special dietary needs)
  • Do I want to breed the fish

Next up, I look at the equipment I will need…


What Fish Tank Filters to Buy

So I’ve been looking into what type of fish tank filters I need for my freshwater fish tank and there are many variables to consider.
Fish tank filters with large and fast throughput are not necessary in a small aquarium and even not necessary in a large aquarium containing a small number of calm-water fish.
On the other hand large messy fish do require a large and turbulent filter to clean up their detritus and a large volume of bacteria to process it.
On the other, other hand a low throughput filter is adequate for a large tank with many small fish in it.

I’m confused?

External Canister Fish Tank Filters

Usually a plastic container with pump located below the aquarium.

These filters can be any combination of mechanical, biological and chemical depending on the filter media I put in the container.
The water is siphoned into the container because its below the water level in the aquarium, passes through the filter media and is pumped back into the tank.

Internal Canister Fish Tank Filter

A submersible pump is located on top of the filter media container and all is submerged in the aquarium.
Water is drawn in through slits in the side of the container, passes through the filter media and exits via the pump at the top.

Hang-on Power Fish Tank Filters

Consist of a plastic box containing the filter media hung on the outside of the aquarium.
Water is drawn into the filter via an intake tube hung over the edged of the aquarium. The water passes through the filter media and returns to the aquarium via a channel integrated into the bracket holding the box to the side of the aquarium.

Under Gravel Fish Tank Filter

A very effective biological filter with a large volume of media, the aquarium gravel or sand bed.
A large plastic plate full of holes is laid on the bottom of the aquarium and covered in 5 cm of gravel or coarse sand. Uplift tubes are fitted to the plate. An air-pump pumps air into the bottom of the uplift tubes and by the airlift principle water is drawn through the gravel/coarse sand and up through the uplift tubes and back into the aquarium.
As the water from the aquarium is drawn down to the plate it brings with it the solid and liquid waste in the water into the gravel/sand bed where the friendly bacteria eats it.

Water Changes

One last note.

Biological filters take care of the ammonia and the nitrite produced in the aquarium but over time the concentration of nitrate increases.
Aquarium plants can take care of some of this nitrate but not all.
So, regular changes of water is necessary. Not all the water. Only 10 – 20% at one time.
And if I’m leaving the fish in the aquarium while I’m doing this, I need to take care and make sure the new water has the same chemistry and temperature as the existing. Or, my fish will suffer.