"I have a 5,000 gallon pond and this sits behind my waterfall. This product works well, but the bulb needs to be changed every year and the screw cap lid makes this difficult. The electrical cord is in the lid and each time you screw the lid it twists the cord. Leave A LOT of slack in the cord to accommodate the cap removal. This year I am forced to replace the entire clarifier due to the wires twisting/breaking off at the cap location.
The replacement bulbs are easy to find, but not cheap. Even though tetra states 14 month bulb life, you need to replace every 12 months - preferably in spring when algae blooms are at their worst. The bulb strength declines with age. Do not touch the bulb with your fingers - the fingerprints alone will damage the UV output.
The quartz clear sleeve is not essential, so it is not necessary to replace.
For the reviewer who said the bulb broke and can't find replacement bulbs anywhere - the bulbs are offered everywhere online, but rarely in your standard pet store. This is a specialty item, as are many pond items. Either order the replacement bulb online here or try to find a local pond specialty store. Local pond stores are very rare - I say order online."