For my own information, are you actually filtering concentrate? I assume you're filtering juice prior to the concentration step? I can't imagine filtering such a viscous product.
no, we don't filter the concentrate as you're already figured out, it would be a bit difficult for filtration. When we finished the filtrationprocess we go into concentrating the sugar between 69°Brix and 73°Brix (depends on the product).
In our company everyone has another opinoin about this topic. The new conclusion is that only the first filter is a CCP and we're going to use the third one only for clarification. that means if there is a damage within the second filter the charge will be blocked though the next step would be another filter.