The problem I was trying to solve that no one else was doing is ballast system using strickly pumps, no piston style, or compressed air versions with compressed air hoses running along the tether. I know this is possible, but I am struggling to find information on it as it seems most people are using weights to achieve neutral bouyancy or using alternative ballast systems instead of pumps. Im sure there are people using pump method, but I can’t find any. Below was the closest I could find, and where I was refering to when I said someone recommended in another post to use peristaltic pumps.