Air pump sizing Rdwc/dwc

Hi everyone. I'm in the process of designing a rdwc system. I'll be doing it in stages due to financial restraint. The plan is to start with a small dwc system and over the next few weeks-month build it out to its final design. Currently I have a couple of air pumps from some aquariums that are no longer being used. My question is: could someone please tell me what the acceptable range would be for pump sizing? The system will start out with 4 or 5 5 gallon buckets. Eventually I will add the recirculating parts and additional sites. When the time comes I will be getting a new air pump. For now I'm looking for the range that is required for say every 5 gallons or per gallon and I'll math it out from there. Thanks

Doesn't take much really. Remember compressing air heats it up, so you don't want to oversize the pump or you heat the nutrients up more than absolutely necessary.

If going with RDWC, consider the waterfall method. Thats not going to add as much heat and actually works better IMO. Plus who doesn't like the sound of a mini waterfall?

I got a nice EcoAir5 commercial air pump for about $120Can. 1300gph and comes with a nice chrome 8 outlet manifold. Using it to aerate my dugout now. Can be used to pull vacuum for purging too.

I will actually use the waterfall method on the return to the reservoir. One less airline and stone. I had been looking at a few ecoplus pumps on Amazon. Would 5 lpm per bucket be enough to ensure that there is more than enough at full maturity?