Fluval Flex 32.5g Build

  • #1
HI everyone, I'm new to the site but excited to be here and learn from you all! I just recently got back into the hobby, or at least I'm more 'serious' about it this time? Not sure how to word it I guess but I had a 20gal tank that had been set up for probably 10+ years but for the past few years has been, more or less, just on autopilot getting the basics done for it. For a variety of reasons, I decided to completely tear it down and start fresh. I wasn't sure what the new tank would be but once I saw the Flex 32.5gal I was sold and knew that was what I wanted to use for the new tank - which is basically just for looks. So I ordered the new tank and other bits I would need.

Here's the current tank specs.

Fluval Flex Build
- Fluval Flex 32.5gal Kit
- Included water pump and 2 foam filters with activated carbon and biomax inserts
- 2 Aquasky LED lights
- Fluval M 150 Watt Submersible Heater
- 1 Bag Eco-Complete
- A nice variety of live plants
- Driftwood
**I took the following from the old 20gal and move it to the new fluval flex, seeing as the 20 gallon had been up and running until the day I switched everything over I assume that the bacteria from the old tank should seed the new one and jump-start or mostly eliminate the cycle process.**
- Substrate (Eco-complete) - Not sure but I think I had 2 bags of the eco-complete in the 20g...I could be wrong about that though and I ended up leaving behind some of the old stuff behind.
- Eheim Classic (2213) Canister Filter
- Some of the crypto plants (I didn't comprehend how many there truly were. I took what I wanted for the new tank and the remainder is going to a friend.)
- Driftwood and rock decorations

I've got the eheim filter running through the same area as the fluval filter so everything is nice and hidden, I have to admit I really love that aspect of this tank. I wasn't overly thrilled with the amount of biological filtration in the fluval foam filters so I took one out and have replaced it with biological filtration in a mesh bag in addition to the activated carbon and some filter floss/sponge. I'd like to find a container that fits in the area to make removing this all a little easier but it's not a huge deal right now and I may just put it all in a big mesh bag and call it good.

Future Stocking Thoughts...

- German Blue Rams or Electric Blue Rams. One pair.
- Cardinal Tetras (Not sure how big of a school I can get away with...15-20?)
- Maaaybe something else? I'm not sure. Any suggestions on what else might be nice to add or do I leave it sweet and simple?

So far the tank has been up and running for a few days now and water parameters as of today are:
Ammonia: 0ppm - Nitrite: 0ppm - Nitrate: 5ppm - pH: 7.8

Oops! Forgot to add pics. Here are a few pics from shortly after set up. You'll have to excuse some of the floaty plant debris.


  • #2
Hey looks good! I'm not a pro at stocking and can't tell you if those fish will work but- remember that the GBR's like warmer water... so you will have to get fish that match their temperature requirements.

  • Thread Starter
  • #3
Thanks, I'm really enjoying it and can't wait to add fish! The cardinals and GBR's both like the warmer water so I should be fine there, I've previously kept them together with no issues so hopefully that's still the case.
  • #4
Cichlids ? I always thought any type of cichlid shouldn't be kept with anything but other cichlids. But I went ahead and read the info on blue rams and they seem to be ok with communities hey?

And welcome to fishlore! Id so get some blue rams for my community tank if they don't end up aggressive!
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  • #5
I suppose there are exceptions to any rule but, in general, I've found that my german blues co-existed fine with other community fish. I had them in a tank with cardinal tetras and corys in the past and I'm looking to potentially re-create that now but with a slightly larger tank and more heavily planted than the last tank I had. Thanks for the welcome and if you do end up getting rams have fun! I love their personality and color.
  • #6
I’m just wondering if adding a canister helped clear things up. I have the same tank and am using it for masked julies and cadopunks. My tank seems rather cloudy from debris. I just added a Fluval 207 canister to the back part like you did. I was using filter floss in the slots but I think it did more harm then good. I want the water to flow better so the debris will be caught up.


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  • #7
It's worked great for me personally. I left the stock filter as is, threw an extra bag of mixed media (bioballs/rings/ect) in the center section and the canister in the back. My water has been crystal clear. I should add I threw a bag of purigen in the canister as well, I think that has helped a lot. It's quite overgrown now, this is after pulling a ton of plants out...as you can see some of them floating in baggies at the top.


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  • #8
I added bags of ceramic rings from an established tank to both sides underneath the original sponges and bags of carbon. I just see too much stuff floating around and don’t like it. I’m hoping this added canister will help with the water polishing. I know when I removed extra filter floss I shoved in the sides it made more of a mess. This internal filter is new to me so I’m trying to figure things out. I know the biological is great but figured I needed help with mechanical filtration.


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  • #9
Marinus Fatmike42

Can you post pictures of your canister set up on the Fluval Flex? I’m not able to picture how you connected a canister filter to this tank.
  • #10
Sure. Pretty much there’s a piece you can cut out that houses the pump in the back. Instead of a solid top I now have a hole cut out and I have both the intake out outflow going in there. After a few hours my tank is already clearing up. This helped a lot.


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  • #11
I have mine set up similar except I didn't take the back piece out and mine still closes.


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  • #12
I have no idea how true this is but I was told when you add biological from an old tank to seed the new tank you need fish in it to maintain the cycle and without fish the good bacteria dies. I’ve never tried it without adding fish pretty quickly so idk if that statement is true. Might be worth finding out. If it is true, I’ve found Seachem Stabilty to work amazingly!
  • #13
Thanks Marinus and Fatmike42!

I’m thinking about modifying my Fluval Flex 32.5 and this helps a lot!

What canister filters are both of you using?
  • #14
I’m using Fluval 207. I found it on sale at PetSmart so I jumped on it. I think it’s on sale until February 2nd


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  • #15
  • #16
I have no idea how true this is but I was told when you add biological from an old tank to seed the new tank you need fish in it to maintain the cycle and without fish the good bacteria dies. I’ve never tried it without adding fish pretty quickly so idk if that statement is true. Might be worth finding out. If it is true, I’ve found Seachem Stabilty to work amazingly!

I was just going off of what felt right. I barley got back into the hobby after being away for like 12 plus years. I’ve learned a lot since then and things have changed. For my first tank back I have a planted 29 gallon. I tried dr tim’s but ordered it off of amazon and watched my numbers real close. I ended up using like 3 bottles of dr tim’s from amazon and nothing. I think after a month or so my tank finally cycled on its own. I honestly think poor storage of the product is to blame. I can’t really say dr tim’s doesn’t work after using amazon.

My second tank I started a month or so ago. I used half the ceramic rings I had from my established tank and added fish right away. After a week my numbers dropped to zero and after checking it daily for about two weeks they are stable. So I am a believer in using old media from another tank. After giving my established tank time to recover I used the dirty filter floss I have for water polishing and added it to the top of the sponges just for good measure. I’ve since removed the filter floss when I bought my new canister and I know it will take time for the bacteria to find its way into my new canister filter.

Mostly I’m just using the new canister for mechanical filtration. I really wasn’t happy with the built in filter of the fluval flex. I’m happy biologically. Just not mechanically. Too much debris floating around for my liking.
  • #17
I’m sorry to highjack this thread but my water finally cleared up. I think it’s been a little under 48 hours. I don’t know if it’s because of the new canister or the fact that I angled the outflow of the original filter to add more aeration and surface tension. Either way I’m happy. I could re angle the outflow to under the water again and see if it clouds up and I will have my answer but anyways I should just leave it alone.

Any thoughts on what I should do? I’d love to hear any.

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