Switch to decrease voltage?

[Bobscreekboy]

So I built the livewell in my jon and Im using a 800 GPH bilge to circulate the water in it. The pump actually runs alot stronger than I would like so I was wondering if anyone had an idea to resist the voltage and make my pump run slower. Some sort of dimmer switch I guess but I dont know much about it. I have a 3-way toggle switch wired in already so Ill be able to run the pump on the full 12 volts when I want to pump water out, or flip the switch and run the resisted voltage to circulate water.
Any ideas on a specific type of switch? Thanks

 

[krawler]

If you want to get real fancy, you can try one of these dc motor speed controllers
https://www.electronickits.com/kit/complete/motor/CKMX033.htm.

 

[dkuster]

I think it would be much easier to control the water flow of the pump mechanically instead of electrically.

For instance, this let's you control both the direction and flow of the water:

https://www.basspro.com/Attwood®-Adjustable-Spray-Head/product/18337/-643554

You will not harm a pump by restricting its output. But _never_ try to control the flow by restricting the input!