Simply Koi and More Koi

I have a new pump on my Nexus and have set it up so that it can either pump direct back to the pond or through a couple of heat exchangers, a heater and a bubble bead and I suspect, if it does all that, the flow will be somewhat reduced.

I have a spare pump ready for when/if my new pump dies but as both have 5 year guarantees, I was thinking that if I put 1 pump before the heat exchangers and bubble bead etc as it is now and one at the other end of the line, say just before the bubble bead, that would improve the flow and would give me more options - while still having the ability to run with just 1 pump if 1 died, than if I just went and got one bigger pump and then throttled it back if I was going direct from Nexus to pond (especially as 'throttling back' bu pushing against a partially closed ball valve contributed to the early demise of my last 'bigger pump').

Would it work? Any thoughts?

Thanks, Martin

You might struggle because flow rate is also controlled by the size of the pipe.
Are you suggesting running two pumps of X ltr through one single pipe of 1.5"?

No it won't work

after the amount of flow is equal to the smaller pump any increase in flow created by the larger pump will result in a huge head loss (friction / disruption in flow..or just plain ol blockage)