I don't know why someone has not stated the obvious yet. You are trying to use the WRONG pump for your application, plan and simple. You are NOT going to find a DC powered pump that can handle 9' of head effectively. They are just not built for that. What you need for your application is a reeflo pump. A snapper or dart gold would be ideal. They can push massive amount of head pressure and are not negatively affected by necking down the flow rate with a gate valve on the outlet.
No, they don't have a fancy pants DC power supply with neat lights and functions, but what they do have is build quality that will outlast nearly every pump on the market, fantastic customer service, and a 5 year warranty. Show me a DC pump that has a 5 year warranty? The upwards of $1k red dragon pump.. 2 years.
And to boot, you can actually call reeflo and say this is my situation and they will give you expert advice on which pump, plumbing, etc.
No, they don't have a fancy pants DC power supply with neat lights and functions, but what they do have is build quality that will outlast nearly every pump on the market, fantastic customer service, and a 5 year warranty. Show me a DC pump that has a 5 year warranty? The upwards of $1k red dragon pump.. 2 years.
And to boot, you can actually call reeflo and say this is my situation and they will give you expert advice on which pump, plumbing, etc.