After seeing goldfish aquariums at people's houses, offices, etc., I have noticed that a lot of people do not fill the tank completely but leave a couple of inches without water. Some people leave even more than that. I guess this is somewhat of a pet peeve for me because I always like the water to be high because it seems to look nicer (to me anyway..) and gives the fish more room. The filter also makes a lot less noise if you have a hob filter. I know that after a while some of the water evaporates...but there are some people who just don't fill it very high even after a water change.

Am I the only that has noticed this? Do you guys do this with your tanks? I read on the other sticky about filtration that if the filter is not at the proper level with the water flowing onto the surface, the water does not get as much oxygen and the filter does not work as well. Just wondering if you guys thought it was a personal choice or if it isn't a good idea.

water hitting the surface breaks it ..making more 02 ..I like mine to be full but when it gets warmer I drop the level a bit because warmer water holds less o2 and I like to create as much of it as I can..but yes it's noisy and my hubby claims he can't hear himself think. ...I always tell him cause he's not

I always keep mine full to the top. I agree, I think it looks a bit better to not see the water line.

If you want to fill it up to the top then you need to add a airstone..and make sure the airstone doesn't make the tank overflow

I have an open-top tank so the water evaporates very quickly. Since I do waterchanges weekly, I don't really feel like putting in the effort to dechlor and add more water when I'll be changing it out in a few days.

Is this because of less oxygen? And when I say I fill it to the top I don't mean the actual top of the aquarium, just to the point where the water line can't be seen.




I understand what you are saying, the water line also goes down on mine but I just make sure and fill it when I do the water change. I am talking more about people who don't ever really fill it to the top...

I think some tanks are designed so you can't fill them up all the way. My new acrylic is about a half inch shorter in the back than in the front. I didn't notice till I set it up, so the water in the back is up to the top, but in the front has a visible water line. I'm not sure why it's designed that way, but it might be as mentioned before, to ensure co2 exchange and to prevent overflow... Hmmm.

I think a lot of times when we see tanks with low water in offices, etc, it's just because the water has evaporated and nobody's bothered to top it up/do a water change

I always top mine up completely. If the filter doesn't disturb the water surface enough, I add an airstone. But like you, I hate when the water drops down to where you can see the line.

or Ihave done this ...fill the tank to the top ..than turned on the filters and that drops the water line

my tanks have a gap at the top because I rely on the water returning from the filter, and a powerhead to agitate the surface and oxygenate the water. If I place the outflows below the water line, that won't happen. I suppose I could rely on just the powerhead and raise it higher but then I would be wondering if the filter is running properly because I won't be able to see water flowing out of it. I like being able to see the water moving because they all get a visual check when I'm on my way out the door to go to work. Anyone with a filter problem will be noticed right away.

It can get noisy though, and my Honey is always asking me to "turn down the fish"

i always fill mine to the top cuz i dont like seeing the waterline. The only tank i leave about an inch is the 29 gallon and thats cuz i did a bad job putting on the background so it doesnt reach quite to the top on one side and i've been too lazy to fix it. I might do that sometime but not yet lol.

We don't fill quite all the way and you can usually just barely see the water line. It has to be the ay because we have an internal filter (in addition to our HOB) which is suctioned to the back and it can't be raised up any higher than it is without bumping against the top. If we put anymore water in it would reach above the spout on the internal filter. Works out for our fish too because he enjoys bubbling 'at us' as we walk by, or even when we don't (I've tested the oxygen, we have plenty, its just a habit of his). If the water line was above the visible level, he wouldn't be able to see us while he did!

Fred, I guess I am just not well informed, but how do you test the oxygen? I would like to try that with my tank.

You can get a Dissolved Oxygen test-- you'll probably have to get it online as I doubt Tri-Cities has a LFS that carries them!

Acidstars, we have the Red Sea oxygen test, which works great, after finding the Tetra one to be entirely unreadible.

Ok, thanks. I will look up that up.

I usually keep mine about an inch from the top. Maybe cause by the time I get it all cleaned & refilled I'm about to fall asleep & I'm afraid I'll OVER FLOW IT! Not really (although I DID run it over once....man did I move fast!!) I guess it's just a habit.

When my son lived at home, he liked it filled right to the wooden-grain trim. He didn't like to see ANY gap at all!

Just a preference really! With all my filters & a 5 foot bubblewall thingee lack of air is not a problem!

lol i overflow my 5 gallon all the time awhile ago i took out the ornaments and filled it right to the top, then started putting in the ornaments not realizing that it was so full so when I put my arm in there it overflowed and went all over the carpet hehe luckily my mom didnt see. Then another time on that same tank my mom came and started talking to me all of a sudden i thought "oh no i was filling my tank!" so I turn around and the water was everywhere! lol and theres been other times with that tank

There's nothing like the unmistakable sound of water pouring over onto THE FLOOR!!!

I usually fill my tank an inch away from the top...... that way my two HOB filters make bubbles......

i dont like it to the top because the air stones "spit" too much water up and it makes a mess....plus its an open air tank and im afraid they will jump out.

I filled my tank to the top once and one of my fish jumped out.....and survived. Which is why you should NEVER fill to the top if you don't have hood.