I will admit, I was writing this review earlier and I wanted to give it less stars but really it can be user error.
I watched two videos of someone using this exact syphon and someone using a larger version. I will say the technique that I used in the video I posted is the best for this exact syphon. There are directions on the package but I didn’t like that you have to dunk everything into the water..
I only dunked the syphon in the water and then pointed it straight up until the water almost reaches the green part. Then I dunked it in again to fill up the syphon and then started to use it. Just make sure you have the end of the tubing in a bucket (or something to catch the water) way lower than your tank. I tried to have my little bucket on the same level (table) as my tank and it so anything. So that was MY BAD.
I really would prefer one with a pump instead, so I could just get it going right away. But this is great for the price.