Where should the unit be placed?
In a dry position with good air circulation- beneath the tank if possible. Never position it under the tank hood!

When the tank is dark, a blue glow can be seen emanating from the tank return pope from the UV filter; is this normal?
Yes perfectly normal. It will do no harm whatsoever to fish or invertebrates as the harmful rays will be filtered out long before the visible blue rays can be observed.

Can the length of tube life be extended by switching the unit on for only 12 hours each day?
The practice is not to be recommended as, although the tube life will be extended, the aquarium will be left unprotected for unacceptable periods. The whole point is to provide continuous protection.

Can cloudy water be controlled with a UV sterilizer?
Yes. If it is caused by free-swimming algae or bacteria a sterilizer is usually very effective.

Some models claim to be suitable for suitable for both marine aquaria and ponds, can this be right?
Possibly. Tests have shown that the optimum cavity space for marine applications must be no more than 6mm and this could be used on a pond as well. But if the cavity space is 12mm, or even greater, it is suitable for pond use only. If the model you are considering does not specify cavity space, look for one that does.

Is there a simple way to know when to change the ultraviolet lamp?
Yes. Write the date for renewal on the unit and in an aquarium log or diary.

Will a UV sterilizer kill the hair and slime algae already in a tank?
No. It can only kill the spores that pass close to the tube in the unit.

What redox level should the aquarist aim for?
Many fish-only tanks will be fine at reading of 250-350 mv. Sensitive invertebrates are best between 350-450 mv, but no livestock should be kept at levels approaching or exceeding 500 mv.

How can the hobbyist tell if ozone is in the main tank water?
By testing with a residual ozone kit available from a well-stocked aquarium retailer.

What are the effects of a residual ozone livestock?
It damages the gills of fish causing them to flick, scratch and breathe heavily. Death occurs in severe cases. Coral invertebrates will fail ti display properly for long periods and, like crustaceans, can die for no apparent reason.

What is the correct canister packing to operate an undergravel filter?
If a reverse-flow undergravel filter is in use, extra biological filtration is unnecessary within the canister and only mechanical media should be used.

How can canister maintenance be made less of a chore?
Maintenance is considerably easier if twin valves are fitted to both the inlet and outlet hoses. The syphon need not be broken when the canister is removed and the risk of water leakage is much reduced.

How can algae be discouraged from forming inside the hosing?
A useful tip to exclude all light completely from the hosing by wrapping it in strips of thin black plastic, thereby depriving any algae of all light. In theory, the algae should not form not form at all.

Why has the impeller become noisy in its housing ?
The impeller can become noisy for several reasons:

1) there is insufficient water flowing past it to lubricate its action
2) there is air trapped in the impeller housing
3) the impeller, or impeller housing is worn.

Avoid very cheap canisters filters models as construction materials tend to be inferior and they can become noisy in a short time. High quality, but more expensive filters are always a good investment.

What should be done if the waste liquid is colourless and copious in quantity?
The skimmer requires further careful adjustment to air and water flow. This situation is not uncommon with new set-ups.

How often should the wooden air diffusers be replaced?
To maintain maximum efficiency renew air diffusers every two months. The internal body of the unit can be cleaned at the same time.

Does the collection cup have to be emptied of waste liquid every day?
No, most modern skimmers have a bleed-off tube re-directing the liquid into a drain or larger container to be emptied once or twice a week.

Is it essential to use ozone with a protein skimmer?
No, many skimmers work very well without the use of ozone, although their efficiency can be markedly improved with its use.

Can more fish be stocked if a trickle filter is fitted?
No. Trickle filters should be seen as a means to improve water quality and not as an excuse to increase livestock beyond a reasonable level.

Do trickle filters reduce the need for water changes ?
No. A 15-25% water change every two weeks should be standard practice for every tank whatever the filtration.

Will trickle filters reduce nitrates?
No, a separate denitrifying filter will be required, although this may be housed within the trickle filter.

Is extra turbulence required in the showertank?
Experience has shown that extra circulatory pumps are usually needed in the main tank to supplement the return flow from the trickle filter.

Is it better to use plastic, ceramic or coral gravel in the filter?
Each model will come with a recommendation from the manufacturer as to which medium suits their own product and this should be followed.