Tropical Fish Tank

It all starts with fresh water

Like us humans that need good air to live, fish need good water to survive in a tropical fish tank.

And there are two aspects to this; the water chemistry and the water quality.

Water chemistry is all about the amount of organic and inorganic substances in the water that affect the acidity or the alkalinity of the water

Water quality is all about the amount of undesirable, mainly organic, material in the water.

Water Chemistry

There are three main elements (excuse the pun) to the chemistry of tropical freshwater aquarium fish keeping; hardness, pH level and salinity.

Now that’s not to say that all fish need the same water. And so when I select the fish for my tropical fish tank I need to make sure they can tolerate similar levels of hardness, pH level and salinity.

Water Hardness

I can tell if I live in a hard water area or a soft water area simply by the amount of lather in my bath water.

The level of hardness is mostly affected by the amount of calcium dissolved in the water and is measured by the number of parts per million of calcium carbonate in the water.

One important point to remember is that a water sample can be measured as soft, that is containing a small amount of calcium carbonate, yet still be rich in other minerals. And soft water fish that come from waters that are soft and with small amounts of other minerals will not fare well in artificially modified water because the amount of calcium carbonate might be corrected but other minerals in the water remain.

Fish originating from hard water areas may adapt to a softer water environment but fish originating from soft water areas may not be able to tolerate a harder water environment.

Water hardness is measured by a process called titration. This involves adding a small amount of special solution to a water sample until the sample changes colour.
Test strips are also available. A sample of water is put on the strip and the test strip changes colour. The colour is matched against a chart to work out the hardness of the water sample.

pH level

The pH scale measures the acidity to alkalinity of any substance.
The pH level is measured on a scale from 0 – 14 where 0 is is dangerously acidic, 14 is absolutely alkaline, with 7 being neutral.

The scale is logarithmic. The curve is not a straight line. That is, a substance with a pH value of 8.0 is ten times more alkaline than a substance with pH value of 7.0 and one hundred times more alkaline than a substance with pH value of 6.0

The pH of water is affected by its mineral content and by the amount of carbon dioxide and organic materials in the water.

The majority of fish can live in free water with a pH level ranging from 4.0 to 9.0 and a maximum annual variation of 0.5. So this is the environment we need to produce in our aquariums.

And it goes without saying that when selecting my fish I need to consider fish with similar environmental requirements.

The pH level of water can be measured with a pH meter, a field kit or a basic litmus paper test.


How much salt is in the water and the most common element is common salt, sodium chloride.

Measured in parts per thousand. Tropical seas having a typical saline level of 35 gm of salt to 1 Kg of water.

More commonly measured by taking a reading of the specific gravity using a hydrometer.

However the SG of a liquid varies with temperature. Typically a saline solution with 35 ppt has an SG of 1.026 at 15 DegC and an SG of 1.024 at 25 DegC

And then there’s brackish water a halfway house between marine and freshwater solutions. With a typical salinity of 15 ppt.

But that’s only really a concern for marine aquarists. For now lets focus on freshwater aquariums, yes?

How to Adjust the Water Chemistry

I’ll be pretty lucky if I can take water straight from the tap and find it suitable for fish to survive and flourish.

Making the Water Harder

To make water harder add calcareous decor materials like coral sand. There are also salts available that can make the water similar to that of Lake Tanganyika.

Making the Water Softer

To make the water softer takes a little more effort.

Water Softening Resins.

Hard water is passed through the resin and comes out a lot softer. However the chemical process converts the calcium ions to sodium ions. So although the water coming out is softer it is also still rich in minerals and unsuitable for most soft water fish species.

Rain Water

Rain water is usually depleted of minerals and neutral or slightly acidic. Unfortunately it does collect contaminates on its way down so to make sure it should be strained through activated carbon to remove the residual contaminates before further treatment.

Pure Water

The safest and most effective method of providing soft water is to use distilled, de-ionised water or pass the water through a reverse osmosis machine.
All mineral salts and organic contaminates are removed.
But so is all the free oxygen needed for the fish to breath. So the water needs to be aerated before introducing any fish.

Adjusting the pH Level

Increasing the pH level can be achieved by adding calcareous material.
For a quick fix add a small dose of bicarbonate of Soda. But check the hP levels between doses.

Decreasing the pH Level

Making the water more acidic is best achieved by using a filter containing peat.
Only use pure peat. Horticultural moss peat without any fertiliser additives can be used or buy a proprietary product.

There are also chemical pH adjusters which should be used with care because the effect is dramatic and instantaneous.

Buffering the pH Level

Fish waste and plant byproducts are slightly acidic and will over time reduce the pH level in the aquarium. Counter this by including some calcareous decor. As acids are produced the pH level reduces. The acids dissolve the calcium carbonate which makes the pH level rise again.

Other Water Parameters

There are also two more chemical related parameters that need to be considered: Oxygen content and temperature.

Oxygen Content

Fish need oxygen to breath.
In the wild river water is oxygenated by the flow of the water over rocks and waterfalls. In lakes by the waves and surf increasing gas exchange at the surface – carbon dioxide from the water replaced by free oxygen from the atmosphere.

Adequate oxygen in aquarium water is ensured by providing a reasonable amount of water circulation.
This can be achieved by passing a steam of air bubbles through the water. This increases water circulation bringing the oxygen depleted water at the bottom of the tank to the surface to be re-oxygenated at the water-air interface .
Movement of the water surface will increase the carbon dioxide – oxygen exchange and is achieved by directing the outlet of the filter towards the surface of the water.


Fish are very susceptible to dramatic changes in temperature. Most fish cannot generate body heat and must adapt to the temperature around it. When the temperature falls the fish are sluggish. When the temperature rises their metabolic rate increases with a corresponding increase in appetite and rate of breathing. As water temperature increases the amount of oxygen decreases making it harder for the fish to breath.

Water Quality

The quality of water is affected by organic and inorganic contaminates when drawn from the tap and also contaminates introduced when the water is in the aquarium.

Inorganic Contaminates

Tap water contains small quantities of various metallic salts either naturally or through environmental pollution. Also it may be contaminated by passing through old lead or copper water pipes. Water supply companies also add chemicals like chlorine and chloramine to the water supply to kill bacteria. Now while the levels of contaminates in the public water supply may be fit for human consumption, they may not be safe for my aquarium fish.

How to Purify Tap Water

Chlorine can be removed by allowing the water to stand over night or running the tap water under pressure into a bucket.

Chloramines and other nasty toxins need to be removed by adding a water conditioner.

Improve the water quality even more by using a tap water treatment filter which will remove most nitrates, phosphates and sulphates.

Inorganic contaminates can also be introduced into the aquarium by introducing unsuitable decor or accidentally adding insecticide spray, furniture spray, paint fumes and the like.

Organic Contamination

Organic contaminates may be already in the tap water used to fill my aquarium.
The tank occupants, fish and plants, are the main cause of organic pollution inside the aquarium.

This is controlled naturally by the nitrogen cycle.

The Nitrogen Cycle

The nitrogen cycle is natures biological way of dealing with waste products.

The cycle starts with the decomposition of dead plants and animals and the excreta of animals. The decomposition breaks down the material into highly toxic ammonia and associated compounds.
A bacteria called Nitrosomonas eat this ammonia which converts the ammonia into a less toxic nitrite.
Another bacteria called Nitrobacter eats the nitrite and converts it into nitrate.

Nitrate is not harmful to fish and is a natural plant fertiliser.

Nitrosomonas and nitrobacter bacteria are aerobic, they need oxygen to survive and the bacteria inhabit any suitable surface like wood, sand and plant leaves.

In nature the nitrogen cycle is continuous and creates a balance. However in a confined space the nitrogen cycle processes need a little help. And we help out nature by biologically filtering the water in the aquarium.

Another reason to filter the water is to collect all the solid waste and uneaten food which if left in the tank would cause some serious pollution on its sown.


Aquarium filtration systems operate mechanically to remove solid waste, biologically to remove the toxic ammonia and chemically to remove other unsavoury toxins.

The basic principle is that the tropical fish tank water is passed through a material that traps the solid waste.
This filter material is usually plastic foam or gravel. But on its own this mechanical filter will get clogged up very quickly and will need frequent cleaning.

So I need to allow the mechanical filter to grow its own biological filter.

Biological filtration

Biological filtration uses the nitrogen cycle bacteria to treat the waste collected by the mechanical filter.
This bacteria needs a surface to cling to, to live and to multiply.
Suitable filter media for biological filters include sand, gravel, expanded clay and specially designed plastic shapes that have large surface areas.
This media acts as a mechanical filter to begin with but as the nitrogen cycle bacteria increases the biological filter effect kicks in.

So, take note, a newly installed biological filter needs time to get established. Do not introduce fish into the tropical fish tank until the filter system has matured.

Chemical Filtration

Chemical filters work best in a high flow of water and also act as a mechanical filter requiring periodic cleaning.
The chemical media include activated carbon and zeolite. Chemical filter media are also available to remove nitrates and phosphates.
Chemical filter media have a useful life and will need replacement after some time.

Well that’s only the beginning of our journey into keeping freshwater fish in  a tropical fish tank. Next up we focus on the various filters available…


Home Security Tips Take Action Today to Secure Your Home

Before you spend any time considering and spending any money on a wireless burglar alarm system, there are many improvements you can make to your home security using simple and practical anti-burglar devices.

First, you need to think like a burglar.

Home security tips Number 1: Take a critical look at your home security from the outside. From the street, from the back and from your neighbours gardens, both sides.

Home Security Perimeter Fences

The back garden is the route most often used by intruders to access your home. And with the modern ninja-type burglars even a 2 metre high solid wood or brick wall is no deterrent.

Top the wall or fence with a 300mm high trellis, weak enough to break under the weight of a person trying to climb over it. The intruder will either injure himself or at least make enough noise to attract attention.

For added home security add a few strands of barbed wire camouflaged by the horizontal stringers of the trellis. Or nail these home security spikes to the top of the fence.

Front garden fences should be no higher than one meter and the same for any trees, shrubs and garden ornaments. This will make sure that anybody in the front garden can be seen from the house and from the street.

And if you are landscaping, consider gravel path around the house instead of paviors. Small stones are cheaper than paving slabs and have you ever tried to walk silently on a gravel path?

Home Security Gates

Solid wooden gates may offer some privacy but they are the easiest to climb over. Make the outside surface smooth without any crevices that can be used as a foothold.

Ornamental iron gates are easy to climb over by the very nature of the design, so consider a transparent panel on the outside to stop the intruder from using the ironwork as a foothold.

Two padlocks are better than one. One at the top and one at the bottom and if the gate is not used very often a heavy chain and padlock can be used.

And if the burglar is really intent then make it difficult for him to lift the gate off the hinges. Weld a metal piece above the hinge pins so they cannot be removed.

Garden Sheds

Garden sheds need to be made burglar proof: Not only because of the value of the equipment inside but more to stop the thief from using the ladders, hammers and crow-bars stored there to break-in to the main house.

Doors and windows need to be secure. Fit the biggest hasp-hinge-staple that the door and window frames can support.

If the garden shed is not that substantial and could easily be broken into then consider not storing in there garden tools like spades and shears as they provide perfect house-breaking-into tools. Or, maybe chain them altogether and then secure the chain to a very heavy object. A work bench for example.


Garages are also used to store garden implements, DIY power tools and the like. Perfect house-breaking-into tools that an opportunistic thief could use.

Normal up-and-over garage doors are usually secured by a simple lightweight centre lock. Not good, with a little noise easily opened. Secure the door with a mortice type lock designed specifically for up-and-over doors.

Side personal doors need to be secured the same way the back door is secured, especially if there is an internal door into the house from the garage.

Front Garden

Keeping the front garden tidy with trimmed hedges and shrubs will deter the occasional intruder as there are no places to hide.
Make the front of the house clearly visible from the road so that any person entering the property can be seen.
Keep cars, bicycles and toys secure inside the garage.
Always close and lock the garage door.

Back Garden

The rear garden is the preferred entry route for professional intruders as it affords more privacy.
Keep it tidy, eliminate the hiding places, put gardening equipment away after use.
Garden ornaments suitable for breaking glass or window frames need to be cemented in place or given away. Do you really need all those gnomes?

Back Door

The back garden is the most secluded part of most homes giving home owners privacy but also allowing intruders easy access to the back door without being seen by the neighbours. Therefore the back door needs to be especially strong and secure.

Fit a 5-lever 2 bolt sash lock at waist height and locking bolts at the top and at the bottom fitted to the strongest part of the door.

Fit hinge bolts to increase the strength of the hinge side of the door

Any glass panels in the back door need to be unbreakable glass and fitted to the door from the inside so the window glass beading or putty cannot be removed.

If unbreakable glass is not available then install ‘burglar bars’, a metal grill, across the window on the inside.

Sliding Patio Doors

Patio doors may look good and for sure when fully open allows the Summer weather into the house, but they are very easy to break into.

Some sliding patio doors can even be lifted off their track.
In this case close the gap between top of door and inside the top track by inserting short sections of wood in the track so when in the closed position the doors cannot be lifted.

Or anti-theft devices can be purchased – not to stop the door from being stolen, but to stop burglars from entering the home.

Modern patio doors are for sure a lot more secure but can still be supplemented by added home security measures.
These usually require a little drilling into the door frame and then into the sliding window frame. Fit one in the bottom frame midway along the sliding window and one on the side frame about waist high. Can be tricky to install especially with the sleek, narrow frames available today.

It can be difficult to install additional home security devices to uPVC sliding patio doors because of the complicated designs needed to strengthen them. So when buying patio doors pay particular attention to the security methods incorporated into the design.

If nothing else then fit removable lengths of 30mm by 30mm hard wood sections into the bottom track to stop the sliding door from, well, sliding.

Hinged Patio Doors

Hinged patio doors are usually two doors wide, hinged on the outside edge, swinging outwards and locked in place in the middle. By the very design they are not very strong and can easily be opened with brute force and a crowbar.

Secure each door with locking bolts at the top and at the bottom.
And as the doors swing outwards fit hinge bolts top and bottom to make it difficult to remove the doors by removing the hinge pins

Patio door glass panels

Replace ordinary glass with laminated glass. Laminated glass is like car windscreens, it splinters but is very difficult to penetrate.

Front Door

The most used door so needs to be easy to open yet impossible to open without the right keys.

The door itself needs to be made of solid wood 45 mm thick and fixed to the door frame with 3 strong 100mm long hinges.

The door frame needs to be solid wood and screwed securely to the walls every 600mm

A normal rim latch is just not strong enough.
A 5-lever mortice deadlock needs to be fitted as well. Fit the second lock 600mm above or below the rim latch.

Fit a spy hole so that you can see who is at the door before opening it

Also fit a door chain. They are not that strong but will allow you to open the door a few centimetres to talk to a visitor while still obstructing access to unwanted visitors.

Letter boxes

A letter box opening in the door allows limited access to a thief:

Don’t leave a spare key hanging on the inside.
Don’t fit security devices that can be opened by a double-jointed long-armed villain.
Fit a wire mail basket over the opening (on the inside) but remove the bottom so any object pushed through the letter box will fall to the floor out of reach of the thief

Fire Exit

While keeping all doors and windows secure from intruders there must be one recognised fire exit route in case of fire or other calamity.
Make sure all family members know the safe way out and do not secure any deadbolts when the home is occupied.


Aquaponics a Sustainable Food Source

Aquaponics is a food production system combining aquaculture and hydroponics in a symbiotic environment.

Wow! Better explain some of that.

A food production system: growing vegetables and rearing animals for eventual human consumption.

Aquaculture: Fish farming. The farming of aquatic organisms like fish, shellfish and underwater plants.

Hydroponics: Growing plants without soil. All plant types can be grown in inert substrates as long as there is water and the water contains the right plant nutrients.

Symbiotic: A relationship of mutual benefit. A close and long-lasting relationship between different organisms that usually benefits each organism.

Aquaponics is not a new food production system.
The Aztecs grew plants on Aztec-built islands. The plants being fed from mud and waste material.
The Ancient Chinese allowed fish to swim amongst the rice plants in the rice paddies.

But it wasn’t until the late ’90’s that academia became interested and proper research undertaken.

How Does Aquaponics Work

In nature organic matter decays and mixes with the soil. Bacteria breaks down the decayed matter into nitrites and nitrates that plants use for food.

Aquaponics takes advantage of the nitrogen cycle in nature. Fish waste is broken down into nitrites and nitrates which are then fed to plants. As long as the fish are fed and the water chemistry is correct the symbiotic relationship flourishes.

Combination of Aquaculture and Hydroponics

Aquaponics uses aquaculture for raising fish and hydroponics for growing the plants.

The only input to the system is fish food.
The fish eat the food, excrete the waste into the water. The extrament is converted into a nitrites and nitrates that the plants can use to grow.

Three main components make up an aquaponic system: Plants, fish and bacteria.

Aquaponic Plants

Many plants thrive in an aquaponic system, however you need to select the right plants based on the maturity of the system and the number of fish in the fish tank.

Green leave vegetables like chinese cabbage, lettuce and water cress grow well with medium nutrient needs.

Tomatoes, cucumbers and peppers need high levels of nutrients and a large number of fish in the tank

Aquaponic Fish Types

Fresh water fish are the most common fish for your aquaponic system.

Tilapia the most popular because they can tolerate crowding and when they are grown they can be eaten.

If you don’t want to eat the fish then koi and goldfish can be kept.


Nitrification, the conversion of ammonia from the fish effluent into nitrates is the reason why aquaponics works.

nitrogen-cycleNitrosomonas are bacteria that converts ammonia into nitrites.

Nitrobacter are bacteria that converts nitrites into nitrates.

It’s the bacteria that makes the whole system work.

The waste produced by the fish is consumed by the bacteria converting it into plant food, the plants eat the plant food in the water helping to keep the water quality safe for the fish to thrive.