For my 8,000 liters of pond to poor performance

At first I had a UV clarifier with 9Watt from the garden center for around 80 euros. When, after about 3 years of the quartz glass bulb was broken, there was not a spare part for it. Then I bought the Berlan UV-C filter in March 2012. Last year was a cool, rainy summer, this year shows that the device Berlan apparently not enough for my pond with 8,000 liters. At first I thought the lamp was already broken, because the window showed only a slight glow. However, the lamp is still ok, a new brought a bit more brightness, but no improvement in the pond. Therefore I change back to a more expensive device for which there is now spare pistons. I give it 3 stars Berlan BLF111UVC device = "not bad", because for 4 stars = "Like" it is not enough in my pond.

What struck me: While the other quartz glass bulb of one piece was Berlan has glued a glass vial in a plastic receptacle. Of course also holds, but the glue is already crumbles, the plastic spacers on the UV lamp to the inside of the bulb is extremely brittle after one year and breaks with a light touch. The UV radiation makes plastic and each adhesive brittle, here the life is so limited life (planned wear?). Whether the glass bulb really consists of especially UV transmitting quartz glass, I can not consider the new device I pay in any case attention to proper quartz glass.
When Berlan light filters the UV lamp does not start electronically, but a thick Balla transformer, which is close to the plug in the cable. So start with flickering fluorescent lamps. This device should therefore never be operated with a timer or start often shortened my knowledge the life of the expensive UV lamp that.

I put a photo of the device under customer photographs, because the ballast transformer is at Berlan (and many others) can not be seen.