Fluval Flex 32.5 Filtration concerns/questions

[Cantusaurus]

Hi, I just have some questions about the Fluval 32.5 filtration. I have had the tank for over a year, and for the last couple months I have been invested in improving filtration, and making sure the tank is cleaner in general. I Would siphon the back chambers fairly regularly (it's very annoying, but it helps). But I've recently pulled the trigger and bought some Intank Media baskets that will arrive soon (Since my DIY ones are not the most efficient).
BUT my main concern is the filter box itself. I noticed that sand and sediment would be on the bottom of the filter box (in the box with the return pump).
I assumed at first it was just kicked up sand etc that got carried into the filtration but then realized that didn't make sense since it would have to travel through my filter media.


I then found out that there are gaps on each side of the filter box.
I cut a small piece of egg crate and superglued small thin pieces to hopefully cover each side enough for debris not to flow through.
BUT I then noticed I saw some sand and debris again. Theres a good amount too. Is there a gap where the wall meets the bottom glass? Because that would explain some of the sand and debris being pulled through.
Do I have to siphon again and try and block this huge possible gap with some plastic crate and glue?
I really do not want it in the back since it is annoying to take out my skimmer and return pump, and siphon it out. I'd rather it stay in the sand so I can either gravel vacuum it out, or stir the sand and let filter floss take it out

 

[Fishyj]

Sounds like you have a bad seal, I would guess it to be lower in the tank. I have the same tank. The back chambers are a terrible to clean out. I love the tank but the filtration in my opinion is, that it’s just a bad design. Hopefully this winter I can redesign the filtration to work better for me.

 

[Cantusaurus]

Sounds like you have a bad seal, I would guess it to be lower in the tank. I have the same tank. The back chambers are a terrible to clean out. I love the tank but the filtration in my opinion is, that it’s just a bad design. Hopefully this winter I can redesign the filtration to work better for me.

Hmm ok, yeah that makes sense.
I think I'm just going to use super glue gel, and the edge of eggcrate to create a barrier. And hopefully that works. Yeah like the filtration is both good and bad in my opinion. Like the intakes being at an angle kinda makes filtering in water better since it helps with water on the bottom to be moved out easier, but just the direction it travels, and the places detritus can get stuck in is annoying. I'll let you know if I see improvements with this implementation. Ugh, I'm very conflicted.
Thanks though

 

[JReef3]

I have the same tank and just installed some InTank media baskets this afternoon as I also felt the stock filtration is lacking in the Flex. I looked down in the bottom of the sump area and there was a bit of debris down there but I can't say whether it was sand or detritus. The way the filtration is designed, as your photo/diagram shows, the lower intake vents are pretty close to the sand (depending on the depth of your sand bed) so sand could likely get in those narrow channels pretty easily I'd think. As for the red circles you drew, I don't believe there is supposed to be any passage through there or unfiltered water would just go from the overflow inlets straight back to the return but at the same time, I don't believe there is silicone there either, just a fairly tight fight between the plastic and glass. Even while wet, you may be able to use some frag epoxy or superglue gel as you suggested to ensure it's sealed if you can reach down there.

Here is a photo I took of the back of my Flex after I leak tested it when setting it up. You can see a little water at the bottom and it looks as though it is seeping under the plastic partition.

 

[Cantusaurus]

I have the same tank and just installed some InTank media baskets this afternoon as I also felt the stock filtration is lacking in the Flex. I looked down in the bottom of the sump area and there was a bit of debris down there but I can't say whether it was sand or detritus. The way the filtration is designed, as your photo/diagram shows, the lower intake vents are pretty close to the sand (depending on the depth of your sand bed) so sand could likely get in those narrow channels pretty easily I'd think. As for the red circles you drew, I don't believe there is supposed to be any passage through there or unfiltered water would just go from the overflow inlets straight back to the return but at the same time, I don't believe there is silicone there either, just a fairly tight fight between the plastic and glass. Even while wet, you may be able to use some frag epoxy or superglue gel as you suggested to ensure it's sealed if you can reach down there.

Here is a photo I took of the back of my Flex after I leak tested it when setting it up. You can see a little water at the bottom and it looks as though it is seeping under the plastic partition.

Thanks for the input!
Yeah I did not think there was a gap at first, but I saw on another thread in the past someone mentioned there being a gap on the left and right side (the red circles). And I tested this about 4 days ago. I had a thin piece of plastic, and low and behold it managed to go right under. Usually the filter will carry the debris up and away from the bottom, especially since there is a plastic piece above it.
BUT I think when things get blown around close to the intake or when turning the pump on and off. The gap is about 2.5 centimeters (It is hard to tell/measure exactly).
But maybe that's not really the issue for me, and it is mostly small gaps in the silicone connecting the filter box and glass.
Tomorrow I will siphon up the crap back there and then use the same method I used previously.

 

[Cantusaurus]

Update: Ugh, I finally got around to siphoning out the back of the tank, and I added some glue. To some flat cut out eggcrate and made a sort of small makeshift internal bracing in a way? The only issue I realized after is that there are all these little dang grooves occasionally going vertically, and while the plastic is flexible some of the plastic/glue might not be in place enough to block any particles from getting through. I may just go down with a small gel glue, and just put some along the edge and just pat it firmly into the corner/seem.
So idk. Hopefully this improves things and I don't see any dust/sand/detritus/etc back there because it is really annoying, and there was A LOT today. (maybe particles got through my crappy DIY media baskets, but sand and other stuff near the bottom shouldn't be consistently getting through especially since my sand is too fine.
I am really hoping this fixes it.
I'm starting to regret getting this tank. I like that it was cheaper than other alternatives and I liked the design, but the way some of the stuff is implemented, and the things you do not realize at first are adding up, in time and in money.

 

[rueric]

How did this work out for you? I have the same tank and am concerned that the filtration media I have is basically useless as water is able to bypass all of it.

 

[maunmaun]

That's a pretty old thread but glad to find I'm not the only one with this problem. I just received my tank and noticed the bottom seal came unglued from the plastic partition on the whole front length.
Lucky is my tank is not set up yet so I will redo the seal tomorrow before water testing it

 

[Fetto2730]

Any updates here? We set up our Flex 32.5 3 weeks ago. Never knew about any of this until today. I didnt even notice if i was missing a seal there, as this was my first AIO tank. I do notice that with the Fluval PS1 skimmer installed, and the stock pump, i still have a thin layer on the surface, and debris in the tank, as it looks like not much gets sucked into the overflow. Thinking about upgrading the pump and InTank media baskets next month. I can watch debris float right past the overflow and not get sucked in. Then i can watch my clownfish lay up against the overflow and get half sucked in as he plays, Just dont get it.

I would assume with a deep sand bed, you dont have much to worry about with that seal under the plastic chamber. The sand should plug it up well.