I gradually discovered that whenever i switch off my canister filters for a few minutes while feeding the fishes, the cherry shrimps and otocinclus always try to rush into the glass lily outflow pipe and munch on the algae accumulated there.
So i ended up practicing a maintenance routine which involves simply switching off the canister filter for a longer duration of 15-20 minutes once a week (not too long to avoid starving the filter's beneficial bacteria). This allows the cherry shrimps and otocinclus time to have a nice "bonus" algae meal and at the same time help clean the glass lily pipe too. :)
Here is a video i managed to capture of the cherry shrimps and otocinclus doing some algae clearing work...
The video was originally around 7 minutes long, but i sped it up by 5x to give an accelerated view of how the glass lily pipe is cleaned. Observe how the shrimp at the top of the glass lily pipe consumes the green algae.
On an important "safety" note, if you are practicing this routine, do keep an eye on the shrimps and otocinclus while they are doing the algae cleaning work, there are times when they may get too enthusiastic and start to swim into the pipe to try to get at more algae, like this curious otocinclus at the right side of the photo...
There was once i stepped out of the room for a while and when i returned a few minutes later, one of the otocinclus actually made it past the top bend of the glass lily pipe, and it was busy eating algae all the way down the hose into the canister filter! I had to eventually disconnect the outflow hose just to rescue it.
So if you do spot any of them doing such reckless acts in pursuit of more algae, just switch on the filter momentarily for a split second to create abit of flow and nudge them back out, its much easier than having to rescue them later on. :)