you can suck the slime out. i used 1/4" airline tubing and syphoned the slime out, the small tubing sucks the water out nice and slow so you can get the slime without draining the water too quickly. new tanks tend to get a diatom algae bloom so it's normal that it's happening, adding the ph will help though. your ph is too low though, you need to raise that. get a buffer and add it to your wc water and work at getting it up slowly.