Do not believe Diatom filters or UV sterilizers to be effective at combating the ICH parasite due to the stage of Parasite 's life cycle in which the cyst's (white spots) fall from the fish and into or onto the substrate.
Filters mentioned, can only remove that which is suspended in the water not that which is on or in the substrate. They might catch a few of the cyst's as they fall from fish but many,many,would fall to the substrate.
Easiest way to prevent ICH is through the use of a quarantine tank for all new fish before they are placed in the main tank and ,,by following the prescribed dosages and directions on medications for treatment of the parasite. This usually involves the removal of carbon from the filter during treatment, and treating the tank for up to a week after all signs of the parasite are no longer seen(white spots).
Is also important to maintain clean water in the tank = zero for ammonia,zero for nitrites,and nitrAtes are best kept at around 20 ppm. Weekly water changes of around 30 percent and vaccuming the substrate with gravel vaccum should also help.
Also important to keep fish that appreciate the water you have ,with respect to proper pH, and hardness. Fishes often exhibit ,symptoms like fin rot,fungus,ICH etc when water does not suit the fish . Is therefor wise to keep fish that appreciate alkaline water which is slightly hard , in this type of enviornment,, and keep fishes who enjoy soft (acidic) water in water that suits them. Proper temp is also important, If water and temp don't suit the fish, they become stressed which often leads to sick fishes.
ICH in my expierience is nearly always a result of new fishes added to the tank without quarantine period ,or due to enviornmental issues.
Fish you buy at the store can be carrying the ICH parasite without showing the common whie spots ,that is why quarantine tanks are used by many for new fish purchased.
Hope some of this helps.
Last edited by 1077; 07-27-2010 at 03:50 AM..