Turn the bass down on the amps. Including yours. Then look to acoustic treatment if you need it, but don't spend money unnecessarily.
It's a tough concept sometimes, but EQ can be used to adjust for room problems. If you're using it to establish tone, stop it. The first thing bassists do is turn up the bass to shake the walls - gets that feel in right? But guess what? So do your guitarists. That's what sounds best when you're trying to get your tones by yourselves. But if your all boosting at 80 hz, you're gonna collide and sound like boomy a**. Don't be a boomy a**ist.
***Perceived tone works best in most cases...so get your tone while in perspective with the rest of the group.***
You'll create space in both your recording and your live sound, and your audience will compliment you for it - even though they won't know why.
If that doesn't work you can look to acoustic treatments. But you'd be surprised how needless they are for most practice spaces I've heard.
Try it and see.

And if it doesn't work, then you can go spend money.
