Air only when the bottom filter is closed

[zenox]

Hello,
I'm trying to use a Kreeper, which requires me to hook it up to the top filter and close the bottom filter so that there is more suction on the top filter. However, whenever I do this, my pump gets air in it (within ~2 minutes) and air starts getting int he pool. Any suggestions what what I should look for to fix this?

[PoolDoc]

Unfortunately, I have no suggestions. Mark (mas985) has spent a lot of time this season trying to help people with suction leaks (what you have) and the results haven't been that great. It's hard to find suction leaks when you are standing there, looking at the piping. Trying to do it over the Internet is nearly impossible. There are just so many different possibilities that it's very hard to check them all.