Lava is very dense rock without the crevices that coral rock has. Lava rock MAY contain heavy metals, but you can't tell without testing.
The reason for using any rock in our reef tanks is for the amount of surface area available for the beneficial bacteria to cling to. Like the grains of sand from sugar sized sand,, there is a lot of surface area in coral rock. Lava rock just doesn't have this. You may as well use slate.
Dry base rock is mined from area that used to be coral reefs. Texas holy rock, Florida base rock, and rock from all the pacific islands are former reefs that are now above the surface. It is the porosity of the rock that makes it suitable for biological filtration.
Jereli, did you have a powerhead in there to keep the water circulating?
Have you added a source of ammonia to feed the bacteria, or start the cycle?
If you are seeing ammonia I would not add the rock to a tank with livestock. If it's starting to see ammonia after a few days it has organic material that is now decaying and creating that ammonia. Get some more tubs and cure it outside of the tank before adding it to be safe.