i'm new to having fish, I have a 29 gallon tank. its been set up for a little over a month now, but I just found out I need a vacuum for the gravel(good thing I have platies) I was wondering how you know what to get. and how they work.
there are a couple different kinds. so far all that I have used are basically siphons, and I have one that hooks up to my faucet, but it really depends on how much you want to spend. the basic ones are usually right around or under ten dollars.
for a 30 gallon I would probably get a medium or large. you just suck the water out of the tank (along with all of the goop) into a bucket, and then refill the tank with dechlorinated water.
that is more expensive but waaay easier and just empties everything directly into your sink-- no buckets needed.
FYI, You can DIY.
Not difficult and parts are inexpensive.
1) Simple Siphon
get hose - length that suits you;
empty soda bottle (2 litre/1.5litre size is up to you) - cut base off;
screw a hole in the soda cap so your hose can fit in snugly.