# Fluval Flex 15: How many gallons for stocking?



## Deanna01 (Jun 18, 2013)

Hi, all! I have a nicely planted Fluval Flex 15 that I'm just loving. I'd like to add some more fish to it using AQAdvisor, but because the Flex has about 3 gallons of its water as sump space, I'm not sure how many gallons to count it as. Does sump space count? Does it count only partially? Not at all? While it obviously doesn't create more space for the fish, it surely helps with bioload?

I'd love to hear your thoughts and experiences!


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## Quagulator (May 4, 2015)

Sounds like you have the answer to your own question: The sump space contributes to bio load dilution, but offers no additional physical space for fish. I would think most nano fish should be okay, my favorite being Chili Rasbora.


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## Deanna01 (Jun 18, 2013)

I am wanting a small community tank and was curious how many gallons I should count it in AQadvisor (which doesn't offer the Flex as a pre-set option yet).


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## Quagulator (May 4, 2015)

For small tanks I would go with physical space, it's easy to put a huge amount of filtration to deal with waste buildup on a small tanks and perform large water changes, so quality of the water is fine, but physical space is not so fine.


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## Carpathian (Dec 23, 2016)

Measure the interior dimensions(excluding rear filtration compartment) and go by that. As stated previously space is important especially when selecting any territorial fish. Out of curiosity what is your stocking currently at. I really want a flex myself but I feel the lighting would be meh and I'd have to customize lid and light which has delayed my purchase.


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## ackphft (Dec 2, 2017)

I have the smaller version of the flex and the square shape of it also has really limited what I'd stock it with. Anything that needs a fair length of swimming space, danios for example, would likely be unhappy not being able to "stretch their legs". I don't know off hand how much wider the 15G is but it's something to think about.


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