Thank you kindly! I had a larger syphon when I first got my tank, but found it frustrating trying to work around plants, and it drained the water level too low before I'd finished cleaning the gravel, even with pausing the flow while moving to different sections, so I bought the smallest syphon in the store so I could around and in between plants. I just use that one now since the tanks are only 15-16 gallons anyway, and it works well I always gravel vac when I do a water change anyway. I've been lazy about cleaning the back part of the tank at times, since it's the most densely planted part, but it's also where the filters are and a lot of plant sheddings end up. I ended up with a few kinds of algae and possibly some cyanobacteria because of too many organics in the water, so I'm being more careful about making sure I raise the sponge filter off the gravel and clean all around and under it, and those plant bases. A lot of muck does gather there! On balance, I'd rather spend time carefully searching buckets for shrimplets than do battle with cyanobacteria *shudders*If you keep shrimps, you may want to have two different sizes of siphon.
One big siphon and one small siphon with adjustable flow rate to prevent the shrimps from being sucked into the siphon especially the shrimplets that are extremely small.
But when you want to siphon out the debris from the gravel, use a smaller siphon with adjustable flow rate.
You can adjust the flow rate to be slower and you can clean just a small area of the gravel.
I also avoid going too close to places where I can't see the shrimps clearly.
I only siphon mostly the front part of my tank where I can see them clearly and places without plants or the open area.
On the 55 gallon though, without shrimp, the bigger the syphon, the better! It's my dad's tank and since he's in his 80s and was neglecting the tank, I took over maintenance before I really got into keeping fish myself. His fish cupboard is full of random fish stuff, and I found two syphons. One had a ridiculously short hose that made it rough to start a syphon or reach the back, the other had a longer hose so I just used that one, for the past year. But cleaning the 55 always left me in pain. Despite being tall, I could only just really reach with the tube over the side of the side of the glass to the gravel and it made to hard to see what I was doing - and reaching the back hurt too, and the hood doesn't help and isn't easily removed. I always worry that I'll get careless and put too much pressure on the front glass while trying to reach, and break it, and by the time I've cleaned the gravel and pulled 5-6 fifteen litre buckets from the tank, my back and arms are killing me. No shrimp to avoid in that tank, luckily, just molly/platy fry. My small syphon is useless in there both because it would take forever to drain enough water and because the gravel in there is much larger and gets jammed in the tube.
I've been planning to buy a syphon with a much longer tube bit so I'd dread water changes on that tank less. Compared the tube sections of the syphons in the store last week, but the length of the tube was the same as the small ones, the bigger ones were just wider and had longer hoses. Then I dragged out the other syphon with the short hose he had tucked away and compared, and the tube was just that bit longer than the other! So I switched the hoses and used the longer tube with the longer hose, and omg, the difference it makes! Kicking myself royally for spending a year doing painful water changes, when I had the equipment to make it so much easier right there
So I agree, the right syphon for the right tank is important! Don't be like me and use a stupid one for a year because you haven't got around to measuring how long a tube you want and you have more urgent things to do. Makes maintenance so much easier to have the right tools.