Cycle, Inverts, & Bioload

[BurlyWizard]

Hi all, apologies if this is a dumb question, but the math isn't adding up in my head for some reason.

 

So when we cycle, the tank makes ammonia to "simulate" bioload waste, so that the bacteria will reproduce adequately for the ammonia created to keep it in check. Essentially like your immune system needs a small amount of germs to prepare to fight off more germs later (is how I like to think of it). Now after the cycle, your tank has bacteria in place to combat a small amount of ammonia from a fish, but we are advised to add slowly, to let that "immune system" catch up with the increased ammonia being created.

 

My question is around CUC and inverts. Most people will agree that CUC critters do not add to your overall bioload, at least from what I've seen. But surely they create ammonia with their waste, yes? So in terms of a new cycle wrapping up, and adding first tank-mates. How do you balance the speed to add your full CUC if they technically don't add to the bioload? Is there some element of "10 hermits = 1 fish" or a rule of thumb? 

 

I ask because I'm currently cycling an invert-only tank, which will be made up of mainly crabs and shrimp. Just looking to better understand how Ammonia & Nitrates will interact just after cycling with multiple inverts of varying types and sizes. Happy to cross-post this in the invert section if necessary.

 

Thanks!

[Murphs_Reef]

They do add the the bioload, just not significantly as fish or bigger animals do. 

That said I would always spread out adding cuc to a new tank regardless as there is a limited food source.

 

I do like your  immune system analogy

[seabass]

4 hours ago, BurlyWizard said:

So when we cycle, the tank makes ammonia to "simulate" bioload waste, so that the bacteria will reproduce adequately for the ammonia created to keep it in check. Essentially like your immune system needs a small amount of germs to prepare to fight off more germs later (is how I like to think of it). Now after the cycle, your tank has bacteria in place to combat a small amount of ammonia from a fish, but we are advised to add slowly, to let that "immune system" catch up with the increased ammonia being created.

For dry rock, yes, well sort of.  We are providing the ammonia without organics, to feed the nitrifying bacteria (your tank's biofilter).  These bacterial colonies adjust to the amount of ammonia being produced, so by making slight changes to your tank's bio-load, we are giving the bacteria time to adjust.  So, yeah, essentially what you said.

 

4 hours ago, BurlyWizard said:

My question is around CUC and inverts. Most people will agree that CUC critters do not add to your overall bioload, at least from what I've seen. But surely they create ammonia with their waste, yes? So in terms of a new cycle wrapping up, and adding first tank-mates. How do you balance the speed to add your full CUC if they technically don't add to the bioload? Is there some element of "10 hermits = 1 fish" or a rule of thumb? 

I would say that your tank's cleanup crew does add to the bio-load, just as you stated, by consuming food and creating waste.  As far as equating inverts to fish, one might use how much they eat.  If starting with dry rock, there is no other food source (besides other members of the crew), so you can make a judgment based on how much you feed them.

 

In addition to your cleanup crew, even your corals will add to the bio-load (especially corals we feed like LPS, but basically anything that eats).  This seems more clear with animals that we feed, but an ecosystem develops where food is produced and consumed without actually adding food to the tank.  This ecosystem usually develops slower than it takes for the nitrifying bacteria to adjust to its presence.

 

4 hours ago, BurlyWizard said:

I ask because I'm currently cycling an invert-only tank, which will be made up of mainly crabs and shrimp. Just looking to better understand how Ammonia & Nitrates will interact just after cycling with multiple inverts of varying types and sizes. Happy to cross-post this in the invert section if necessary.

The bio-load of an invert tank can be quite substantial, especially those inverts which require feeding.  It's just easier to observe and evaluate the load by how much we feed.  Plus, that's usually a good enough indication to estimate the bio-load.

 

We've been primarily looking at input, but we can also look at output (as you implied).  This could be the byproduct of the nitrogen cycle (nitrate), or waste created (and hopefully removed during maintenance) from the inverts you have introduced.

 

Fish can be particularly large, and active, which requires more intake of food than typical inverts we keep in nano reefs, such as dwarf hermit crabs.  However, the relative impact is the same.  Obviously, herbivores in our cleanup crews aren't typically fed, as we tend to keep them to manage algae growth; but they count too.

 

I'm not really stating anything that is dramatically different than what either you or Murphych did.  But hopefully it answers your questions.