For some reason the filter in not quiet
830586
There is a propeller/screw type element at the end of the curved pipe - pull that pipe and element up and off the unit... clear any debris in there and make sure that the propeller/screw type element is seated nice and tight and straight and not fouled with any hair or other such stuffs... then re-seat the components. That should stop any rattling... What kind of noise are you hearing? It's not absolutely quiet, there is a bit of splashing that you can hear.
830587
If it's grinding then it may have sucked in some sand/gravel, lift the top while running the filter by pulling on the flow adjustment tab, a piece of sand or gravel may come out, then gently set the lid attachment back into place. this may resolve the issue. If that doesn't help try rinsing the filter out and make sure the little impeller rotor isn't bent or broken.
1568615
I noticed this in one of mine as well. HCO Customer Service responded quickly: "The filter in front of the lens is supposed to be floating around when it's not powered."
1032460
Without actually seeing the unit, my guess would be much like Mr Salazar's comment that something must be restricting the flow out of the bottom hose unless your pump flow in is more than what the lower hose is able to flow out of the filter.
308794
it is possible the valve is no good or is not lined up to completely shut of the other valves while in the filter position. their should be no water coming from that valve also make sure your pressure valve on the left of that hole is closed.
664166
Sorry, I can't help with this. I returned the item due to poor performance and didn't have it long enough to have to clean the filter. Good luck.
327600
Most likely the filter is dirty and not absorbing the water as readily. Either than, or the air is not as dry as it was last year-hardly likely.
32825
Make sure the pump is properly seated into its base and the suction cups are properly secured the back. Mine was a little loud as well until I did this. Also if it starts to overflow it's because the filter is dirty
1280770
Make sure the filter is placed correctly and the fountain is on a level surface. What you are experiencing is not normal.
2137691
Possibly filter needs changing or fan needs to be cleaned. You can check for solutions on youtube if you cannot find solution in owners manual, we were able to fix a problem we had starting it up this summer. But ours is working well now.
2187384
Check to make sure it is going on the right rail. I had the same problem the first time I changed my filter.
145665
Are you sure you got all the air out of the lines and the filter? Might have to shake it a bit to get it all.
869941
Next time improvise a filter in front of it, like a cloth or some screen on it so it won't get dirt, and you just need to clean the filter you had place. :)
516418
That is odd. Sometimes I get a gurgling sound but that is it. Should be silent. Remember to run filtered water through it. Might want to hit up seller.
1927681
Aqueon QuietFlow Internal Filter Cartridge Small 2pk. Usually if you look under the "frequently bought together" section it shows this filter.
31678
I've never had this problem with mine. Did you rinse out the filter well before placing it? That's the only thing I can think of that might be the cause...
1543338
I had that problem. There is a filter in line. Cleaned it and the flow was fine again.
937750
It's a bit louder than other sponge filters but not that much louder, what's loud is probably your air pump