Galacticraft liquids such as fuel, oil, and sludge need to have some substance put to them. I noticed that you can't float or swim or drown in them. Players should be able to swim in the liquids because it would be more realistic. The bacterial sludge should also give the poison effect when you're in it, as if you're being infected, unless you have armor and thermal gear on and on full health. The 4space liquids are more like liquids where you can swim in them, so galacticraft should do the same.