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Many people feel a check valve is a bad idea as it tends to accumulate things and could clog the line.
The theory I've seen most commonly as of late (Catalina 34 message board, Practical Sailor, etc.) recommends installing two pumps. One is a low volume, small diameter hose at the lowest point of the bilge. The other is a higher volume pump intended to kick on when there is more significant water to be removed. The smaller pump will have less volume dropping back when it shuts off due to the smaller diameter hose.
Having said all of that, unless the backflow is kicking the pump back on, it's probably of limited value to rejigger the whole thing. Lastly, have a look at the hose. If you can get it above its drain point closer to the pump, you would reduce the amount of backflow.