Air Stone issues with Commercial Pump + Manifold/splitters

I've tried using the commercial pump setup twice in the past. I'm hoping to try it again in a few weeks, but I know I need to change something first, and that is where I need your help.

Attempt 1: Networked, no pump dwc bubbler system. Air pump -> manifold -> stone in each bucket (line lengths kept identical, same stones)
Failure 1: Stones were not flowing at the same rate, ever, slower flowing ones clog faster, so they slow down until they stop, root rot, ...

Attempt 2: Networked with small pump, bubbles in every other bucket.
Failure 2: Water height differences from bucket to bucket only contributed to the problem, air stones cloggedd within 4 weeks.

In the end the issue seems to come down to "the path of least resistance" issue. I think the only way to fix this is to have something meter the air out. Is there a such thing as a metered manifold? Any idea on how I could DIY this if not?

I want attempt 3 to be:
2 small pumps circulating
All buckets with air stones, metered manifold, commercial air pump.

But I'm tempted to toss the commercial pumps and get a bunch of 1 outlet pumps.

How about using lever valves? (https://www.google.co.uk/search?q=air+pump+manifold+lever+valve)

If you're not happy guessing relative flow rates how about a gas flow meter (rotameter) like this: http://www.aliexpress.com/store/product/Air-flow-meter-gas-flowmeter-rotameter-oxygen-meter-flow-94mm/713759_32373001818.html

1. Find out your pumps total flow rate.
2. Divide that by the number of buckets you're using so you know how much each bucket should receive.
3. Use the flow meter(s) to set the air output appropriately.

If you don't want to buy a flow meter for each bucket then you could just use it to check output at one section and then move it along.

I have the levers, but they don't help when you can't monitor or replace the stones easily. The buckets in the 4 corners are nearly impossible to get to when the room is full of plants.

I was hoping there was a manifold with a moving part, spinning, that would work something like a cap/rotor on an older car. Something that forces all the pressure down 1 outlet, but switches outlets quickly...