sell it to me
I will add another metering valve, to make them inline for fine bubble adjust.
so two metering valves together look GOOD.
Put more metering/needle valves inline, the adjustment is much precise, I am going to give it a try.
I plan to use the SMC AS1000 valves I have, to make them two each group(inline, their inlet/outlet are really easy to connect), so finer adjustment.
putting two needle valves in conjunction will not make them more precise.
The flow will only be as high as the valve that has the lower flow, kind of like only as strong as the weakest link. Whichever valve is set to a higher flow does nothing, because the flow will always be lower due to the other metering valve.
If you have the second needle valve set more closed than the first, pressure will slowly build up between the two metering valves, until it is the same before and after the first valve. After that, the first valve becomes useless and does nothing to the flow of the system, because the second metering valve is the only limiting factor of the flow