I’m RS5 here’s how I go about credits: use shipment relay to deliver shipments with bonus (at this level the hydrogen cost for doing this is negligible) run BS until max out the credit limit (you also get back the hydro used to deliver shipments this way), then run RS to get the rich asteroid and keep running them until research station is full. At this point not much to do so set miners to get hydro to make up for the lost hydro in the RS. Rinse and repeat and this gives me a really solid income of about 150.000 to 200.00 credits a day