I bought this unit about 5 months ago before we were going on a long holiday to replace a smaller Fluval filter. Initially we were very pleased as the water was noticeably clearer, the aeration was much better and the UV seemed to control the problem with algae we had been having. The first disappointment is that it is difficult to clean. You have to prise the suckers off the glass, unlike the Fluval which just slipped easily in and out of a bracket. Then it is quite a struggle to separate the bottom chamber from the main body to clean the filter media, which is a little basic, at best!! However, after 5 months the bubbles from the unit suddenly went microscopic in size making the tank look like fizzy soda. We tried to control this by cutting back on the air, but in the morning the pump had stopped working. On removing the unit we noticed that the watertight tube containing the UV light was full of water. How the fish werent electrocuted we dont know. The outer glass seal enclosing the UV light seemed to be intact so how the water got in there we will never know.As a result we will be replacing this with a more reputable brand. I have put 1 star but in reality if something is potentially electrically unsafe, I am not sure that it shouldnt have 0 stars. However it did work well for 5 months.