Soft water has a lower level of calciferous salts than those found in hard water. Freshwater is classed as being ‘soft’ when it’s General Hardness is 6 degrees or lower. The Hardness of your local tap water can be measured quickly and accurately using one of many available Hardness test kits.
Softening Your Water:
If you do have hard water, there are ways and means of being able to soften the water in your aquarium.
Firstly, a ‘softening pillow’ can be placed inside your filter. These resemble large ‘tea-bags’ which work by allowing the water to pass over an ion-exchange resin and can be recharged using aquarium salt, thus can be used over and over again. At first, the softening pillow will need recharging fairly often, but the need to do this will reduce as the water softens. Once the water has softened, it is then wise to then carry out your future water changes with Reverse Osmosis Water (see next paragraph). This is a comparatively slow method of decreasing the water Hardness in a tank, and which some people may find a little fiddly, with continuous recharging of the softening pillow.
Secondly, Reverse Osmosis (R.O.) water may be used in place of your tap water for small regular water changes on your tank. Here tap water is passed through a semi-permeable membrane that holds back approximately 95% of it’s mineral content. The water that is produced is very pure and will need buffering with essential trace salts and minerals to sustain your chosen fish, although these will not make the water hard again.
R.O. water is available from our shop, and is sold in 25L (6 gallon) containers. The initial cost will be £8.99 for the container itself, and £3.50 for the R.O. water. Then, when you return with your container for a re-fill, you will only then be paying for the cost of 25L of R.O. water, at £3.50 a time. We do also have remineralising salts/trace elements available, which can be added in to your R.O. water for an additional 50 pence.
After a series of small regular water changes with R.O. water on an existing tank containing hard water, you will be able to measure the General Hardness of your water and see that the Hardness is decreasing. If you are setting up a new tank and it is filled with R.O. water from the start, once it has gone through the usual maturation period, it will already be at a softness suitable for most Softwater species.
Other Points Worth Mentioning:
Avoid using decor in your tank which leaches minerals and makes the water hard and more alkaline e.g. limestone, barnacles etc. Ensure that the substrate that you use is lime-free, such as aquarium-grade Silver Sand. This is usually inert and will therefore not affect the water chemistry in your tank.
Softwater systems usually tend to be quite acidic. Some aquarists use bogwood in their tanks for decor. This tends to leach tannins into the water, which actually helps to make the water softer and more acidic. The downside is that the tannin will discolour the water (although some aquarists do not see this as unsightly) but this can easily be removed by adding a little activated carbon to the filter if you so wish.
A slightly more acidic tank will have the benefit of controlling any fungal infections more naturally, and Softwater tanks will generally have far fewer snails, as there is insufficient calcium for their shells to extract from the water.
Softwater/Acid Loving Fish:
You should always try to mimic the natural living conditions of the fish you have decided you would like to keep, for good long-term health and vitality. If they originate from softer waters, then keep them in softer water. The fish will be a lot happier, a lot less stressed (and therefore less at risk from certain diseases), more colourful, and should live a much longer life. You are also more likely to be able to breed certain species in softer water. The following are some examples of fish which prefer Softwater/acid conditions:
- Most South American cichlids e.g. Microgeophagus Ramirezi (Rams), Discus, Angelfish, Apistogramma sp.
- Most loaches ('Botia' sp.) e.g. Clown Loach, Botia dario, Botia striata, Botia almorhae, Botia histrionica, Botia kubotai, Yasuhikotakia sidthimunki etc
- Small South American Tetras e.g. Rummynose Tetra, Cardinal Tetra, Emperor Tetra etc.
- Most Corydoras sp. catfish.
- Most of the beautiful L-number pleco’s (Loricariidae) e.g. Golden Nugget, Queen Arabesque, King Tiger etc.
- Killifish.
If you would like any further help or advice, please do not hesitate to ask a member of staff at your local Maidenhead Aquatics store.