What kind of rocks are these and would they be good for my 55g?

[Blake420]

 

[ahmad.echols]

Bottom pictures cool top picture I don't know

 

[Chaik]

As long as you clean up good and determine they are solid any rocks should be fine for a tank

 

[rlederer]

They look ok but test them with a drop of vinegar; if it fizzes, the rock contains calcium and will increase the hardness and pH of your fish tank. You can also put them in an empty tank or bucket for a week and see if they have any effect on the pH or hardness.

 

[Blake420]

They look ok but test them with a drop of vinegar; if it fizzes, the rock contains calcium and will increase the hardness and pH of your fish tank. You can also put them in an empty tank or bucket for a week and see if they have any effect on the pH or hardness.

Awesome thank you im just getting into the hobby