phxazcraig said:

I've got a 30 gallon reservoir being used in a drain to waste coco system. I'm using all equipment listed in the cocoforcannabis.com tutorials, including a 400gph centrifugal pump.

I have a problem, I think, with the pump moving a lot more water when the reservoir is full than when it is empty. By perhaps double or more. It's causing havoc with my plans for managing EC, and I have wildly different runoff amounts - wasteful.

So I'm looking for a suitable submersible pump with positive displacement so that I get the same amount of water moved per second regardless of water level in the tank. I'm thinking of something in the 300-400gph ballpark, perhaps less. Any recommendations?

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