Not sure about doing that with hose, but I have always had aquariums and you just scoop the big end full of water and block the other end and raise up the big end higher until all the air is out. That creates the suction.
Then you put the big end into the water, careful not to let air get into it. Then the water will be pulled out the big end and out the small end!
I've never found anything that stops algae from the aquarium either, none of those drops or tablets or anything....except cleaning it out, 1/3 to 1/2 of it as needed and scrapping the sides as needed!