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Fluval Flex 15g marine conversion. First tank- here we go!


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Jul 7, 2016
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Columbus Ohio
Well after about a year or so of poking around I finally took the plunge a couple of weeks ago.

Kind of happened by accident, had a friend who was going to be moving and breaking down a tank so I decided it was time to build my own now that I wasn't going to be able to gawk at his anymore :)

It's been a bit of a wild ride thus far and am a little worried I'm in for troubles but I'm taking the punches as they come and everything seems to be ok as of this moment lol.

Basic setup:

15g Fluval Flex tank
Fluval Sea cp1
Finnex 50w drop in heater
Red Sea Pro
5# dry pukani
20# CaribSea live sand
3.3oz Bio-Spira
  • -Stock pump
  • -Stock foam filter & media
  • -Stock light
  • -No skimmer

As of now, on day eleven and already have some livestock in the tank. Levels are ok but I'm worried my test kit or my color vision is off because things seem to be going a little too well for what I expected. I have a feeling there just hasn't been enough time yet.

Wasn't planning on having as much livestock this early but my friend ended up needing to leave town a little earlier than expected. In addition to that, I had just thrown in a pair of juvenile clowns. I was back and forth between one, which I felt was a better choice for the cycle, and two, which I felt was a better choice for the fish. Ultimately I decided to get two little guys and throw them in together. Within three days I also added another two fish. In total, I already have:

Two (2) Ocellaris Clowns
One (1) Pajama Cardinal
One (1) Melanurus Wrasse

Looking to upgrade the internals on the back of the tank, just from poking through here it looks like the evo has some good aftermarket offerings to step up the capability of the tank and even though I haven't found anyone else using a Flex here I've seen a couple videos online so I have a feeling I'll be able to rig something up to have this be a viable setup long term.. assuming I don't kill everything in the tank and/or crash before I can even get my feet on the ground.

Please let me know if I should mess with my scape, I'm worried that the curved arm wont' have enough surface area for corals and corals will be the main focus of this tank so I want to make sure I'm not shooting myself in the foot with my scape.

Couple pics:

Hoping I can somehow keep all these guys alive through the cycle and everything goes ok! I had a lightweight freakout earlier today but did a lot of reading on the Bio-Spira and am hoping I can recreate some of the more aggressive instances I read about where basically a full bio-load went in after Bio-Spira and everything held together.

Fingers crossed!!

As far as places to go for custom(ish) hardware for the Fluval Evo, which I see a lot more people running in here, where would you point a newbie to look?
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Apr 22, 2015
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You are now hooked! hahaha Great looking tank, I really like that rock!

What is a good measure of success in this hobby? Choose all that apply!

  • Tank Grown Coral Colonies

    Votes: 279 74.6%
  • Colorful Corals

    Votes: 208 55.6%
  • In Tank Coral Reproducing

    Votes: 182 48.7%
  • Coraline Algae

    Votes: 148 39.6%
  • Established Tank Time

    Votes: 128 34.2%
  • Healthy Fish

    Votes: 248 66.3%
  • In Tank Fish Breeding

    Votes: 127 34.0%
  • Other (please explain in thread)

    Votes: 25 6.7%

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