Cannister filter into under-gravel filter?

[budified]

My 30 gal tank came with an under-gravel filter base and 2 plastic tubes, I have an Eheim Pro-II filter (234% water filtration for a 30 gallon stocked at 107% according to AqAdvisor) and fitted the intake tightly into one if the tubes on one corner of the tank and put an air bubbler in the other tube on the adjacent far corner of the tank. I put 2 ceramic tiles starting from the opposite corner from the filter intake, tight enough against the glass and each other that tiny pellets cannot fit through, and covered the rest of the bottom filter base with the standard plastic aquarium gravel and a layer of 1/4 - 1" chunks of granite that I tumbled and polished in a rock tumbler.

My question, is the ideal way to utilize what I have?

The filter is very powerful and would suck in any fish I will have in the tank, so it is sucking through the under-gravel filter, but 2'×2' of the base is covered with ceramic so the suction comes from a small strip of gravel at the front and roughly 1' × 1' at the side with the filter intake.

 

[budified]

This is the tank, lacking a few plants and another piece of driftwood.

 

[StevenF]

The filter is very powerful and would suck in any fish I will have in the tank, so it is sucking through the under-gravel filter, but 2'×2' of the base is covered with ceramic so the suction comes from a small strip of gravel at the front and roughly 1' × 1' at the side with the filter intake.

I don't think you need the tiles. with gravel over your UG base the filter would have 288 squar inches of area to pull water through. That large increase in area will reduce the water flow the fish feel considerably. Additionally the gravel on top will slow the flow even more. However with the tiles you concentrate the flow through the narrow strip and the fish will probably feel the flow there. If the flow without the tiles is still too high I would put a valve on the output nozzle of the pump and use that to adjust the flow down to a level you believe is appropriate.

 

[budified]

The tiles are actually for esthetics, as my tank floor is a rather unique combination of:

Tile
Sand in a Pyrex dish for plants and loach bedding
Gravel over the exposed UGF
Polished granite over the gravel (which may end up over the exposed tiles depending on how my tank progresses)

I am not concerned about the flow through the gravel, I was concerned about the suction from the exposed cannister intake tube, as it had no means of keeping the fish in the tank and out of the filter.

Here is a picture showing the variety of tank floor, giving plenty of variety to my aquatic friends.

 

[budified]

After moving some things around to accommodate the plants needs for lighting, and watching the tank for an hour or two throughout the night, I cannot see any draw on the water above the floor grade besides that pellets generally settle to the outside of the tiles. Even in the area directly above the intake tube, particles can leisurely float around with the current above ground. I feel this will be a sufficient filtration method as it seems it will clear out everything that settles through the gravel.