Most of all use air stones at sometime during our fish keeping experiences. Some of us may graduate to the more efficient external canister type filtration systems, making air stones a thing of the past, but for those of us who still use the simpler forms of filtration then air stones remain an important piece of equipment which, in order to ensure optimum filtration within the tank system, we must ensure are always working efficiently.

Air stones come in different forms and are made from a variety of materials. The most common air stones are the inch long cylinder and ball shaped ones that are used in under gravel filters and some types of corner filters. Air stones are available up to 12 inches in length and these particular models are designed to either be of assistance in aeration or to be used purely as a decoration in larger tanks. The air stones mentioned up to this point are usually made from either a glass or sand material. In recent years we have seen the appearance of an ‘everlasting’ model but more about this later. On the shelves of aquatic retail outlets you may also find air stones made out of wood, but these are only of use to those aquarists with a marine set up.

Whichever type of air stone you prefer to use there will come a time when the production of bubbles begins to tail off. This is an indication that the crevices between the glass or sand particles are getting blocked. It is time to either put a new one into use (you should always have a spare air stone among your aquatic bits and pieces) or try, in some way, to unblock the stone already in use.

If you decide to have ago at unblocking the airstone, the best method, in my experience, is to drop it into boiling water to which a few drops of vinegar have been added. When cool enough to handle the airstone can be lightly brushed (if you brush too vigorously the airstone may start to disintegrate) with an old toothbrush, which will dislodge the obstructions. The airstone is then given a good rinse and returned to the tank.

The ‘everlasting’ model (which tends to be the most expensive) can be dismantled and cleaned so that it is able to operate to its maximum potential throughout its life. Basically it is made of a central tube with two opposing cut out sections. At the lower end of the tube is a disc shaped end piece. Polo mint shaped rings slide over the tube from the upper end, the topmost having a simple locking device to keep the rings in position. The airstone operates by allowing air to escape from the central tube through the gaps between the faces of each of the rings.

As with the more conventional airstones, the amount of bubbles does tend to diminish after a while, but this can be easily rectified by dismantling the rings and cleaning them. This should return the airstone to its original condition. I have however found that I can extend the length of time between cleanings by cutting a very shallow cross-shaped groove on the face of each ring. One word of warning – do be very careful whilst cutting these grooves because these rings are made from a thin plastic material and can so easily end up shattered into two or more pieces unless the process is carried out very gently.

To make the grooves I use a small hobbyists’ hacksaw and can claim that I have not had to do any maintenance on airstones of this type for the last three years, so it is labour saving too. Obviously I do ‘rub over’ the stones when doing the routine maintenance on the filters, which themselves have also needed no maintenance for three years as well.



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