When I smoke I try to fill up the water level high so that the water will cool well the smoke.
Maybe its not such a good idea. On many bowls you’ll see the gold rings which are really good indicators of how much water you are filling.
Want a good indicator of your own? If when smoking and you smoke a toke on your hose and you are getting a bit of water in the hose-well thats way to much. Sometimes you’ll fell like a gurgling feeling when you pull on your hose, thats also about too much water.
The type of  hose thickness and its width plays a part since each hose pulls differently.
I’ve purchased a few hookahs and each one has a different pull on it, so again its a matter of experimenting with what you have.
Hookah 1