You will need to shut off you main drain. Main drain is a misnomer, it is better called a deep suction as is the Barracuda. They both pick up heavy dirt only the cleaner will go to the dirt. This makes the MD redundent. As an appendege it is not nessary. With suction going through both they will stick together. So with no need for a MD you should shut it off or better yet plug it with an expantion plug. I hope that explains your problem. Simple fix.
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You will need to shut off you main drain. Main drain is a misnomer, it is better called a deep suction as is the Barracuda. They both pick up heavy dirt only the cleaner will go to the dirt. This makes the MD redundent. As an appendege it is not nessary. With suction going through both they will stick together. So with no need for a MD you should shut it off or better yet plug it with an expantion plug. I hope that explains your problem. Simple fix.