Most often when we are referring to Fish Tank water salinity or hardness where are you talking about brackish water aquariums or ocean water aquariums. On occasions you will have reason to add salt to a freshwater aquarium in order to combat bacteria in your freshwater tank or to assist sick fish in a recovery in such cases in ourselves as raises the salinity or hardness only marginally.

You can measure the salinity in your tank using a hydrometer. You obtain brackish or saltwater for your fish tank by visiting a suitable brackish water or ocean but this may present some problems. Many river systems in coastal areas of Australia contain levels of pollution that would make adding the water hazardous to an aquarium. This is especially so after heavy rain due to acid soil leaking into the water. Around major ports like Newcastle, scientists have recorded a massive drop in the number of green plants and animals living in rock pools perhaps due to antifouling agents from the large carrier and coal ships coming in out of the port. Of course there is also the difficulty in transporting this water. Brackish and salt water aquarium tend to be very large must a lot of water needs to be transported. (Editor – when I lived in Byron Bay I had a 12 foot tank which I was using as an ocean aquarium. I use the blood from a double sized waterbed that fitted snugly in the back of my 4wd ute.  I have an electric pump to connect to my battery ran a hose from the ocean to fill it the whole process taking about 90 minutes. After one too many exploded bladders I became a saltwater maker instead of a saltwater taker.)

You can make your own saltwater using marine salts and ordinary tap water. Marine salts contained more than just sodium chloride, the contain all the trace elements and other salts that are naturally occurring in the ocean. These marine salts are readily available from your pet shop or aquarium supplies shop and the owner should be able to talk to you about the required salinity levels from the fish that they supply

Fish Tank Water Hardness
This is a measurement of the dissolved mineral salts in the water. The harder the water is the more salts it contains. It is typically described as calcium carbonate content, which is measured in degrees or parts per million utilizing a specialized test kit. You will need to be careful about the degrees of hardness as this varies by region and test kit.

Hard water occurs when water absorbs calcium carbonate from rocks of material. In Australia most coastal areas and got very soft water whereas inland areas which rely more heavily on bore water may have extremely hard water. You may artificially create hard water if you decide to decorate your tank with items such as Corals or shells as these contain a large amount of calcium carbonate. If water hardness is can be an issue your fish should avoid such decorations. Slate and granite decorations are greatly preferred to anything with a limestone base.

Was most fish species prefer soft water there are some varieties that have grown up in hard water areas and are thus able to cope or even thrive in such conditions such as cichlids coming from the east African lakes. These species and Coral and Shell decorations will present no problems by noted that not doing so might either as they are hard water resistant as opposed to being hard water reliant on they will do just as well and soft water.

There are several ways to soften water. You can boil and distill it however this is time and energy hungry. You can collect rainwater assuming you don’t have a concrete lined a tiled roof. You can also soften water using an ion exchange resin or process it by reverse osmosis. If you do use were treated in this way to note that will be virtually free of dissolved oxygen and will need to be aerated before being added to your tank.

Some important Terms

Temporary hardness is hardness that can be removed by boiling, and permanent hardness cannot.
Carbonate hardness
is contributed to by carbonates, but not other salts.
General hardness is that which includes all dissolved salts, and is often referred to as total hardness.
Some scientists measure mineral content in terms of electrical conductivity instead of hardness.

PH of your Fish Tank
The pH scale is utilized to measure the alkalinity or acidity of a substance. The scale runs from zero to fourteen, with zero being extremely acidic and fourteen being extremely alkaline, and seven being neutral. Most fish come from water that has a pH between five and a half and nine, although there are some at either end of the scale. Don’t forget the scale is logarithmic, and each step up or down is ten times the previous one. Therefore small variations can have dramatic effects on fish. If your fish tank ph is 6.5, and your fish are supposed to be in 7.5ph water… your water is tend times more acidic than it should be and your fish are not happy.

Thankfully the PH scale is universally accepted so there is no issue with different units as with hardness. Specialized test kits are available and diligent aquarists may want to purchase electronic pH meters. The pH of water is affected by the substances within it. The salts that harden water also usually make it alkaline, whereas soft water is usually slightly acidic. There is really no point in trying to acidify water in an aquarium that is constantly being buffered back to neutral or alkaline by salts from tap water or the decorations. First you need to minimize hardness; otherwise you are wasting your time. Soft water can be easily made acidic using peat filtration. Loose peat will migrate and is placed in a nylon bag or stocking, then rinsed to remove particles. IT is quickly exhausted and should be renewed at intervals established by monitoring pH.

Water can be made alkaline by utilizing decorations that are calciferous or by filtering over crushed shell, limestone or coral. This material should be included in systems for fish that cannot tolerate acidic environments, to act as a barrier versus the acidic effects of metabolic byproducts. Understand though water dissolves calcium carbonate very slowly so if you are doing regular water changes is unlikely a few pieces of coral are going to be our to add enough hardness where hard water is desired. In such cases you will need to use crushed limestone.

Using these methods will produce a gradual change to avoid pH shock. You may need to adjust the pH of new water quickly before using it, although in most cases partial water changes with neutral water typically do not have an ill effect. If you use a pH adjuster, just follow the instructions exactly. Failure to do so can be fatal for your fish. It is preferred to prepare new water in advance or use bicarbonate of soda to raise ph. You can use peat extract to lower it. The dose must be determined initially by adding small amounts to the new water and measuring the ph. You should always treat water before adding to your aquarium.

Water chemistry is actually much more complex than indicated here, because mineral composition varies from region to region. However, there is really no need to simulate the exact makeup of the water s fish are usually able to extract the amount of the vital elements they need.