Hi Sumpfinfishe,
I've used it in the past but because it's so expensive, I switched to an algae concentrate that I got in the states. It was originally developed for the aquaculture industry, but take mix a product for the aquarium trade called "Tahiti" blend.
It's extremely concentrated, and because the phyto is dead, you must feed sparingly. I've used it for a year and half now and found a lot more sponge growth, rotifers, and mysis shrimps in my tank.
Here's the link if your interested
http://www.instant-algae.com/
Regards,
Terrance