Please look at your tubes with the cooler on and see if there are bubbles that are preventing proper flow. You might have to loosen and twist the tube while flow is on the tube to allow bubbles to escape. (turn off the power to the tube first, always wear safety glasses) Cut the silicon hose in and out of the cooler to reduce length. Place cooler on stand to raise the cooler up closer to the level of the tube to reduce head.
When you go to read the manual, you have to translate one small part of it at a time into your own words. (make your own new written manual translation}
There were dead bugs inside my 150 tube when it came from the factory. You could see them swim by every so often.
if it is a real 5000 then you can call or write the factory and an English speaking person will help you.
M
shenhui 900x1200 dual tubes 150 & 60