i'm using the same pump as you.. i use a 'rain pipe' that's used for those stackable OHFs and white tape it to the pipe on the end that the water flows into the OHF. helps to distribute the water a bit and allows the water to hit onto my wool, cushioning the impact of the water gushing out.
i then used a small piece of rock to block the outlet hole which is connected to another elbow to further soften the impact of the water that's once again, gushing out from the outlet hole and into the tank.
if it sounds like what you're looking for, i can help by providing you with a picture for a better idea.
cheers.
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