Lake pump algae issue

[JTO]

I have a 1 HP submersible deep well pump which I use to pull water from the lake for lawn watering. I'm running into an issue where it appears that the algae and seaweed is clogging the intake screens on the pump. I seem to get about 5 minutes of good pressure and flow then it drops off. If I let the pump sit for an hour it goes strong again, then slows down. I'm assuming the rest gives the seaweed time to dispurse from around the screen. My idea is to take a piece of 6" PVC, cut holes or slots in what I'd consider the "top" 180 degrees of the pipe and screen the holes. Put a plug on one end, slide the pump in and clamp a screen on the end with the discharge. If I place this assembly on the lake bed or slightly elevate it I'm thinking the pump will only be pulling water from within the PVC, which is somewhat filtered by the screening. I know I need to allow enough water in so the pump doesn't starve, but I'm wondering if anyone has any other thoughts on this?

Thanks

 

[Speedbump]

A screen large enough that the water getting to the pump isn't moving as fast as it would be going into your suction screen on the pump. I know as the first pump I put in a pond to run a fountain, filled up with minnows in about 20 minutes.