Pressurized Filters

[petevette]

Hi, I currently have a small pond and was thinking about switching to a pressurized filter. I have read that these filters have low maintenance compared to regular mechanical filters. I am a little skeptical about how low maintenance they are. I am afraid it may be a marketing tactic. Has anyone had experienced with these filters. I understand they have some kind of indicator that lets you know when you have to open a valve to let the sludge out. How long does this take? Won't my water level drop considerably by doing this? Just wonder if this filter is worth it. Any help would be appreciated. Thanks in advance.