There are several ways to determine if you have a clogged field. The first is to watch and see if water flows back into the septic tank from the outlet when the tank is pumped. This means water from the field is flowing backwards into the tank. Another is if the water levels in the D-box are above the outlet laterals. There should be about an inch in the bottom of the outlet laterals since the holes are at about 4 and 8 o'clock in the pipe. The last was is to dig a post hole in the drainfield through the stone to the soil below and determine the water level in relation to the laterals.

I do not know what "acid chips" are, this is a new term to me, but acid treatments of drainfields are not recommended since acid tends to help destroy the soil structure.

Tree roots are a problem which are best taken care of by removing the tree or cutting the roots. Probably the best treatment for roots is to put copper sulfate in the distrubtion box if this is allowed in your state. If this is not allowed, a cutting snake can cut them out, but they will grow back unless you take additional action to remove the source. Septic-Scrub(TM) drainfield flow restorer will not have an effect on tree roots. 

If you ahve any other questions, please do not hesitate to call.