New R DWC setup

Might sound silly but just wondered what people tend to do with the large tank that auto fills the main RDWC system. Do you fill with the same solution strength thats in the main system? or something a little weaker and adjust the system on the fly? Does anyone just use it for water and then ad feed to the main system as needed? I havent been able to find much about this online. I'm worried that any feed in the big tank would just sit at the bottom and not be mixed properly. I guess some may stick a little pump in the tank to keep liquid moving? Sounds like this would need a long flex... Any pointers helpful to be honest!

Thanks!

The only thing I put in my auto-fill tank is Southern AG Fungicide & a water pump to circulate. This works really well to keep out pathogens. I add nutes directly to my RDWC reservoir weekly or as needed.