Rena XP2 water return minimal?

I have a rena filstar xp2 in a 45 gallon tank. I will clean the filter and about a half week later the water coming out of the nozzle comes out really slow. why could this be?

A: It could be a number things including the filter is not priming properly on restart, filters although clean may be restricting flow, etc. There have been a number of Q&A's already posted on this subject. Here are some links to those sections:

http://www.planetrena.com/rena-filstar-performance-questions.html

http://www.planetrena.com/Filstar-Rena-FAQ.html

You will need to scroll down the page to find them but there are at least 4 or 5 questions and troubleshooting guides on this subject on either page.