Here is a bit of information from Manky about the Anoxic Filtration System and its diffuser implementation in the system. To read more go to his link in the UK and a plethora of information will be at your fingertips.
“As said in the article, the diffuser is purely to break up the water flow into the anoxic pond to avoid it disturbing the baskets so the design is left to pretty much to the user but there are some pictures for guidance.
Figure 5 and its accompanying description shows a suggested design. The inset diagram below it and the description alongside it shows how that may be implemented to make a simple shut off arrangement that can be used when flushing the anoxic pond.”