Sprayer fill up/trash pump help

Ive never had dealings with a trash pump so bear with me. I rented a farm this year that I have to pump water from a creek to spray with. Borrowed a 3 wacker nueson pump from work. Pump worked a little too good. It would only pump at 3/4 or wide open and it was a dang flood. I thought I could idle it down but it wouldnt pump. Got to looking at harbor freight pumps. 1=35 gpm 2=150 ish gpm and 3= 300ish gpm. For my needs a 1 would be fine, but I guess Im wondering if my borrowed pump has a issue or are all trash pumps a WOT or nothing proposition? I would like a 2 at times if it will pump at 1/4 or 1/2 throttle. Thanks for any advice

With a pump starting and stopping your risk of a back flow condition down into a stream is much greater.
Just something more to think about.

Stream water is dirty and will quickly plugs screens and nozzles too. As for the pump it's the draw that takes rpms in most cases. Make sure the pump is at water level and they should pump at lower rpms. Maybe not idle or 1/4 throttle but surely half throttle.

You can put a valve in line to gate it down.

Pump it into a used plastic bulk tank, let it settle, then gravity or pump with a smaller unit into the sprayer. Jon f has a point on the debris in creek water. Jim

I use a small trash pump like this to fill the liquid fertilizer on the corn planter. It runs at barely above idle and pumps just fine.

Of course I'm not trying to suck the water uphill. The tank is above the pump and the planter is below.

this is what i was doing yesterday. dug out is full to the top and cows sinking to their bellies so i filled the trough for them for drinking. i made a filter for the end of the suction hose. worked good , had nice clean water coming out. tryed without the filter and could not get clean water. no problem sucking water i even idled the engine down to 1/2 throttle. at wide open it will fill this tank in 3 minutes. i also fill sprayer from dug out.

I ran a small 2 inch pump for several years on the one farm back in the boonies and drew out of a nice clean running creek . I installed a foot valve in the suction line used window screen on the basket to filter out any junk and had to lift the water from the creek to the pump about eight feet then push the water up to the sprayer about six or seven feet . Now i never really knew how many GPM it put out put it only took a vary short time to fill a 350 gallon sprayer at between 1/4 and 1/2 throttle . Before i added the foot valve it was always a problem getting prime , but once i did and you manually primed it the first time and the next fill up was just start the pump stand there for a couple min. and shut the pump off . Back in the days i worked in the oil patch we used 3 inch trash pumps to fill farc tanks of 300 BBl. ( 42 gallon to a BBL) and even pushing the water from those Honda 3 inch pumps some times over 500 feet from the creek to the tanks we would fill one in around in around 45 min. So a 3 incher will really put out the water . I know that even my little 2 incher will move LOTS of water wide open as i have only ran it wide open three times and twice was to suck out over 32 inches of water out of my basement and that only took about a half hour .