A word about the manifold.
The way you will use it is to start with all outlets that are going to a diffuser in the full open position. Never turn them all off when the pump is running, as this puts high back pressure to the pump and is hard on it (especially if the pump does not have a relief valve). So start out with full air to all diffusers.
Watch the boil at each diffuser. If one diffuser is getting more air, close down the valve to that diffuser to cut off some of the air going to it. Close it down till you get even air flow to all diffusers. The valve going to the diffuser getting the least air to begin with should always remain fully open. Only close valve(s) partially to diffusers that need to get less air.
Changes are not instant. Make a change then wait a couple minutes to see the results. If your diffusers are at different depths you likely will have to turn the valve almost completely off to the shallowest diffuser. You will think it is off but it actually will require a very small opening to restrict the air flow to that diffuser so enough pressure will develop to push air to the deeper diffuser.
I have one pump that runs both a diffuser in a tiny forage pond and a diffuser in a different sediment pond. The forage pond diffuser is about a foot shallower than the sediment pond. The shallower diffuser was getting about 3/4 of the air till I closed the valve to it nearly completely off. Since that pond is actually smaller, I actually closed the valve off even more than making the boils even, and forced less flow to the diffuser in the smaller pond. So you can tailor the flows to the diffusers if you have a specific need to do so.
I don't have a lot of experience with aeration systems, but I do have recent experience. Others on here have a lot more experience than I do. Hope this helps.
