Use My Fluval Fx4 Canister With Predrilled Holes? Help

Discussion in 'Filters and Filtration' started by Dray, Jul 15, 2019.

  1. Dray

    DrayNew MemberMember

    I bought a Fluval FX4 to use with my 90-gallon tank less than a year ago. Now the 90-gallon is gone and I've just picked up a 130-gallon tank. This new tank has three holes pre-drilled in the bottom. It came with a canister filter and fittings, but it's not any brand I recognize and it's much smaller than my FX4, so I'm pretty sure I'll be better off sticking with my FX4. I'm wondering if it's possible to rig up my FX4 to use in those pre-drilled holes?

    I realize the obvious option may be to dump the canister completely and get a sump. I am hoping I won't have to do that. While I've watched numerous videos and read about how sumps work, I've never actually had one before and am not sure I'm up to the task of figuring it out. I've also heard that sumps can make a lot of noise, and my husband will not tolerate a noisy aquarium.

    Here are the pre-drilled holes in the bottom of the tank. There are two close together on one side, and a third on the other side. I know one hole was for intake, another for outtake, but I am not sure what the third one is for. Maybe a powerhead?

    Here's the filter that came with it:

    And here are the fittings that came with it. They may be broken or missing pieces. They look like mostly PVC pipe and sprinkler fittings.

    Any thoughts about if I can use the FX4, and if so, how I would need to go about it?
  2. Zka17

    Zka17Valued MemberMember

    It does seem that the tank was drilled for use with a sump. I don't like the idea that the holes are in the middle, I would have preferred them close to the back...

    The simplest option would be to cover those holes. You can use bulkheads with stop fittings/caps. Or you can use glass sheets and silicone. Then you could setup the canister filter as it should be (hoses over the rims).

    If you really want to use the canister with the existing holes, you have to be creative. The single hole could be the return from the canister, the two close holes could be the intake. The real problem is that you will need to rise the intakes (and most likely the return too close to the surface), otherwise the water pressure in the canister will be excessive - soon or later it will start leaking. Now, rising the intakes/return by adding a tube to the bulkheads will be unsightly in the middle of the aquarium. That's where your creativity with the aquascape would come handy...
  3. Islandvic

    IslandvicWell Known MemberMember

    The filter it came with is a Nu-Clear model by Inland Seas.

    I recognize them, because Doctors Foster and Smith had them on clearance before they shut down the site from Petco buyout.



    It needs an external pump to be plumbed in-line.

    I guess it could be used as a pre-filter to the FX6.

    I would not discard it. It would not hurt attempting to re-integrate it back in to the system
  4. JayH

    JayHValued MemberMember

    I had a similar setup on a tank once. I combined a canister filter with an undergravel filter. Mine had four holes. Two to pull from under the undergravel filter plate, one to pull from just above the substrate, and one for a return that was a clear tube that went up to the water line and was capped with a tee.

    There's another recent thread here somewhere that might be of interest. It's about combining a canister with a reverse flow undergravel. The output of the canister is sent to under the gravel and percolates up through the substrate. Since the aerobic bacteria in the canister have largely depleted the oxygen in the water, this allows for anoxic conditions in the substrate and encourages the growth of nitrate-eating bacteria. It takes several months for these bacteria to become established, but once they are you can cut back dramatically on water changes.

    With the tank you have I'd give serious consideration to setting up something like that. Use the two outer holes as returns from the canister. You'd want to set up a plate of some sort just above the holes so the water is directed out the sides. With mine, the place I bought all the fittings had something designed specifically for that purpose. Kind of a mushroom cap that glued in place over the hole. The third hole could be used for the intake. If you leave it just above the substrate it would suck up a lot of the detritis.

    You'd likely want to add something for circulation within the tank since the filter setup I described wouldn't create a lot of water movement in the tank.
  5. OP

    DrayNew MemberMember

    You guys are awesome. I'll admit a lot of this is going over my head right now, so bear with me please.

    This video is super helpful.

    All of the plumbing and a pump for the Nu-Clear is included, though it may need a little TLC. From the video, it looks like the Nu-Clear is not really intended to be a standalone filtration, though I think that is how the previous owners were using it.

    Do you think I could use both filters together in a closed system using the predrilled holes without looping any tubes around back and over the top? Maybe have one hole as intake going into the Nu-Clear for prefiltering, then attach directly to the FX4 (maxed out with biomedia), then back up though the second hole?

    If that will work, should I then use the third hole for anything or just seal it?
  6. fa4960

    fa4960Well Known MemberMember

    Based on the parts that came with it I would risk a qualified guess that the third hole is for easy water change, as a minimum for emptying the tank but could also be used to pump water back in.