The trajectory of the flow causes the water returned to the tank to be sent far out into the tank before it reaches the level of the intake. Common sense and a little knowledge of geometry proves that most of the return water isn't recirculating right back into the filter.
being tha the tank is shortest from back to front, the water flows out and down towards the front of the tank, where its deflected again in many directions, one of which (and the shortest of which) is back towards the intake.
Now, if your filter was on one of the sides of the tank rather than the back, you'd probably be right. However its a HOB filter, not a HOS, so not many people use them in this fashion.
In actuality, no the gravel wouldn't restrict the flow too much. It would be no different that attaching a powerhead to the undergravel filter. The magnetic impeller design is common with the AC filters and powerheads.
[color="red]you're right, it is no different than using a powerhead. And using a powerhead on a UGF while common, also has the same effect on the impeller. Of course this is determined by many factors including grain size and depth of the substrate, but its the same effect. Its just a matter of how much the impeller is being restricted. the strain places on the impeller in either case, can cause premature equipment failure. And depending on the amount of strain, it could be weeks, months, or maybe even years if there isn't much restriction. But a powerhead operating under these conditions will not last as long as one operating with no restriction on the intake, unless it it specifically designed to handle head pressure. (which most powerheads are rated at 0 pump head)[/color]
Most people don't have bare bottom tanks, so the word of caution was to save those who don't the headache of sand/small gravel being sucked into the impeller causing premature equipment failure.
[color="red"]I'd be cautious of using such generalizations. Quite a few people here on MFK have bare bottom tanks. While "not many people" you know have bare bottom tanks. A lot more people than you might think, do. But again, this was all covered earlier. I might suggest reading the first 5 pages again. [/color]
In your pictures, you don't show screen or foam, so a lot of people, myself included, would think it wasn't necessary. If you went with smaller holes to prevent gravel from being sucked up, they would easily become clogged with the gravel causing restricted flow.
you're right. In my initial post, I did not show foam or screen, because it is not necessary for a bare bottom application like the one in the pictures. however, later in the thread applications for use with gravel and even sand were addressed (pictures included). Perhaps you could have gained more from actually reading through the thread prior to responding to it.
I'm not sure what your gravel is made out of, but mine are rocks. Rocks which are entirely too heavy to just be sucked into the intake on its own without first being stirred up or disturbed by hand or by your fish. Also, by using slots rather than drilled holes (also addressed earlier in the thread) you run much less risk of gravel blocking the entire opening.
Like I said, with small adjustments, this can be accommodated to fit your specific situation. The initial post was just one of the examples in this thread
Be open to constructive criticism. I didn't say your idea was crap. I merely made some observations based on my experience.
and I am merely making corrections and rebuttals to your observations. Maybe its you who should learn to take constructive criticism.
