Does the 5000ml show up in your Fusion software graphic?
Here is the DDR manual regarding this...
CONFIGURING THE DDR
The DDR container volumes need to be configured. There are three ways you can do this. In Fusion, click on the name of the container on the dashboard; in the native interface via the Module Setup web page or via the Display module navigating to Setup – Module Setup – Config Module. When you select the container (Fusion) or the DŌS module (native interface or Display module) you will see some new fields. In Fusion: Total Volume and Volume Left. In the Native interface: Container 1 & 2 size and Container 1 & 2 volume left. With the Display module: Volume Pump 1 & 2 and Volume Remaining 1 & 2. While the field names might vary, the purpose is the same – indicate the total volume of each container and the amount of fluid currently in them. The capacity of each DDR container is 2 Liters or 2,000 ml. By entering values here (1 – 120,000), Fusion will automatically keep track of your container volume and display that on a graphical tile on the Fusion dashboard. Note that you can use this for a non DDR container up to 150,000ml (approximately 40 gallons). This supplements the purpose of the optical level sensors in the DDR which are positioned in the reservoir to notify you when approximately 500ml of solution remains. These fields when properly completed will enable Fusion to give you additional information about fluid levels in the containers.
Note that if you have a DŌS but not the DDR you still can use this feature with your own reservoir, just substitute your values for those noted above. However the depiction of the containers in Fusion is only available with the DDR. (we know with this DIY discussed here, this last statement is no longer true)