Airstones. I have not used glasswares for airstones before. Based on your video and pictures, I suppose part of the fun is to go shopping around for something that you like and try to fit it into your tank and budget.
As for algae eaters, you can look into the different species of otocinclus catfish. But these guys are quite sensitive and survival rates are low because of the stress they received during the transport from overseas to your local aquarium. They will help you deal with brown diatoms and the softer green algae. They are omnivorous and therefore will eat pellets as well. I think 2 or 3 will be enough in your tank. I have kept up to 4 before in my previous 60cm tank but that tank was more heavily planted than yours. Healthy otos can be a good indication of water quality in a tank.
Personally I avoid siamese or SAE. These guys grow really fast and can be up to 10cm. There are people who are fans of SAE. I removed mine with much difficulties because they move very fast.
Some people like snails to deal with algae. That could be an option. But I can't advice you on that because I don't like them. I used sparkling gouramis to deal with snails.
I also soaked new plants in Algaexit and Anti-snail medications before I put them in my tank. The one time I got lazy was the one time the snails got in....
Lily pipes. In my old 60cm tank, the lily pipe that I used did not help breakup protein films on my water surface. In the end, I went with a surface skimmer. And relied on a normal airstone to improve oxygenation. It was only later on that I found out that different people have different level of success with different designs of lily pipes. So abit of trial and order is needed as the outflow of your filter may also play a part. Actually, I don't see anything wrong with your outflow. So if you have not observed protein film on the water surface... then all looks good.
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