looked on Friday to find the reservoir was low, not empty, but low. What fluid is good to top her off. ive read some places to use ATF (automatic transmission fluid), others say brake fluid , and others say hydraulic jack fluid. which one is best for my boat-leveler system?

DO NOT use brake fluid. Brake Fluid mixed with ATF or Hydro oil will contaminate and cause the lines to swell. The units probably come filled with bio-degradable Hydraulic fluid, I am not exactly sure, but I use ATF with no problems. If the lines are not designed to be brake fluid safe you will have tons of problems, along with the o-rings and seals inside the pump. ATF is the way to go.