Lol happy bday! The sponge filter is fine for shrimp, a lot of ppl only use a sponge filter. Where did you get yours? I might just get one of those instead.
Yeah the dimensions of the 2 are very similar, but the gallon per hour are very different. I think the Palm is a different model. I just started a 2 gallon bowl ($9-10 @ Walmart), not sure if I should filter that too or what to use, do you do water changes or clean your 4g betta bowl often?