Acrylic aquarium problems

[Brolin89]

I bought this used acrylic tank (90 g cube-ish) and since I’m new to acrylic tanks I didn’t think these marks were much to worry about. I figured I could just buff them out… but now I’m wondering if this is a crack…? If it’s crazing, is there anyway to repair it? It’s the front panel too

 

[Timfish]

It's hard to say from the angle but it looks like crazing caused by #3 or #4 spilled on it. A macro shot straight on would help. If it's crazing it might removed if it's not too deep. Search for videos using various grits of wet/dry sand and lapping paper to see how to remove it.