CUC Legit?

somebloke

New member
How does a substrate-cleansing organism have a positive impact on waste levels when they are part of a closed system and produce waste like everything else? That seems to be the conventional wisdom and it doesn't make sense to me.

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I would like to think there is some benefit of having a chain of different animals iteratively processing waste over and over again from fish to crab to worm to.. ad naseum. It's probably safe to assume that having several 'CUC' members means more opportunities to support animals with different functions in a tank. But that's all speculative and not necessary for a decent tank.

It's even farcical the degree to which we are told we must buy a clean up crew. I've got quite the "clean up crew" just by hitchhikers (bristleworms, snails, mussels, chitons, limpets, micro brittle stars, pods, etc).

But I keep hermit crabs, emerald crabs, pep shrimp, cleaner shrimp, an urchin, a few kinds of snails, a sea cucumber, (what else am I missing..) because I want a slice of the ocean, as artificial as it may be. I don't pretend they magically make waste go away. But, they do knock down the unsightly aspects of having animals in a box (filamentous algae, diatoms), keeping the rocks and sand clean looking. In reality, water changes and macroalgae harvesting are my best 'clean up' methods.

There may be other benefits. For example, a piece of dead food under a rock fails to feed any coral (well, maybe not those that feed on DOCs), but having the nutrition of a pellet cycle through many animals many times might mean than eventually something like coral get a nice tasty poop? I'm not sure how much of a supplement this food-cycling is, but it's nice to know it doesn't go to total waste.
 
Semi-related, I think this blog post here should be mandatory reading. It discusses being very deliberative about piecing together a clean up crew. I'm guilty of buying inverts, just cause...
 
Semi-related, I think this blog post here should be mandatory reading. It discusses being very deliberative about piecing together a clean up crew. I'm guilty of buying inverts, just cause...
Did you intend to include a link?

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Semi-related, I think this blog post here should be mandatory reading. It discusses being very deliberative about piecing together a clean up crew. I'm guilty of buying inverts, just cause...
Nevermind, it showed up for me when it white you in my reply but not in your message. Weird

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Could you re-post the link? Not sure why it's not showing up as normal, but I can't click on it either - very weird.

Totally unscientific answer: I know what my water looks like if I let a frozen shrimp decay in my established display tank uneaten vs what it looks like eaten. The first causes bacterial blooms, the second doesn't. I won't entirely pretend to understand the food chain that leads to that end result, but I would speculate that the bacteria that deal with my CUC's waste is established and stable (vs the bacteria that spike when left on their own to decompose the shrimp). Would love to hear some actual science on this though.

Also: CUC (the right ones) eat algae and make the tank pretty. Film algae building up on back glass? Time for more snails...
 
The more complex an ecosystem the better it's stability. That being said most of the hype around getting a CUC is just that, hype. Many will starve and in my experience are a waste of money.
 
Each time an organism eats the waste of another organism it removes nutrients.

Yeah.. I'm no expert in environmental stoichiometry but I've listened enough to Jim Elser, who literally wrote the book and started his career with algae and copepods, to know that this is minimal (Specifically ~5% of the consumed mass). The rest is metabolized and excreted.
 
Totally unscientific answer: I know what my water looks like if I let a frozen shrimp decay in my established display tank uneaten vs what it looks like eaten. The first causes bacterial blooms, the second doesn't. I won't entirely pretend to understand the food chain that leads to that end result, but I would speculate that the bacteria that deal with my CUC's waste is established and stable (vs the bacteria that spike when left on their own to decompose the shrimp). Would love to hear some actual science on this though.

That's along the lines of what I referred to in my first post: "I would like to think there is some benefit of having a chain of different animals iteratively processing waste over and over again from fish to crab to worm to.. ad naseum. It's probably safe to assume that having several 'CUC' members means more opportunities to support animals with different functions in a tank."

Consider that waste from a fish gets processed many times (I think it was Shimek who watched an amount of fish waste go from one detrivore to another 8 times). Animals eat and metabolize for its by-product, energy. Energy is released when molecules are broken down. To answer your question, I would guess that bacteria are less efficient at breaking down complex molecules; intermediaries can metabolize molecules to the point of being more readily available to bacteria.
 
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