Sponge filter?

to me, yes. works teh same as it does when there is one on it.

Yep. Water gets in through the sponge and it comes out on the top of the filter...

It does not look as nive, but does not compromise efficiency.

It is not as efficient. And the longer the lift tube the more water it moves. Easy to prove. Take a sponge filter with 2 different length lift tubes. (you can use a stub of one if you go with the no tube theory) cut a hole in an aluminum pie plate the exact diameter as the lift tube and slide it over the tube so it is just below the top of the lift tube. Fill the tank to the bottom of the pie plate and start the air pump and the timer. Do it again with the other tube for the same amount of time and measure how much water went into the pie tin. You can also do this test with and without an air stone. The smaller the bubbles the more water it will move. I don't use air stones, though, because they are a pain and it takes more air pressure.

You may be right that it somehow affects efficiency, but it still works, if water goes through the sponge and out of the top. Water gets dispersed more quiclky, that is a fact.

He asked if it was as effective. The answer is no. You are right, it still works. You are wrong it does not get dispersed more quickly. If it did, the pie plate would fill up quicker with no / short tube. How could it disperse quicker if it is less water?

rodger said:

He asked if it was as effective. The answer is no. You are right, it still works. You are wrong it does not get dispersed more quickly. If it did, the pie plate would fill up quicker with no / short tube. How could it disperse quicker if it is less water?

Click to expand...

I do not agree with you nor am i going to do the pie plate experiment. If there is no tube to conduct the flow, the water starts dispersing sooner, as it leaves the filter.

But ii really is not important, nor is the difference, in a small tank, ( where these filters are used ) relevant, imho.