how to properly estimate your Bio-Load!

First thing, there is no single theory, rule, or formula to estimate a good bio-load for a tank. But, I believe there is a proper method to figure it out during the tank planning/conception stages.

1) You need to decide on what type of tank you want (reef, FOWLR, FO, etc...).
2) Then you need to decide on the amount of time you're willing to devote to the tank, including potential vacations, power outages, etc. Also consider who else in your house is capable/willing to help out.
3) Draft a list of compatible livestock, obviously this will probably be larger than what will eventually inhabit the tank.
4) Once you begin to know what livestock you want, then you need to figure out how to provide the best conditions for that livestock. The best tanks IME are designed around the livestock.. At this point you'll continue to narrow down the choices based on:

A) the capacity of your bio-filter. The more rock and the more flow you have, the more livestock you can safely support (in theory). Having a sump allows you to "cheat" in a sense by having more rock and more water volume. Keep reading though as this isn't a free pass.

your maintenance routine. Will you be doing 10%, 20%, 50%, or some other % water changes every week? Larger water changes mean you'll be removing more waste and so theoretically you can support a higher bio-load. Remember that this is only as long as the water changes are consistent and sufficient. Thinking you can have a high bio-load by doing 50% weekly water changes and skipping it even once could potentially cause a crash. I would call this living on the edge. If you're going to play the overstocking game you need to know your stuff and have a QT set up at all times as well as take proper precautions and have a thorough understanding of the biology of your tank. There are people who get away with this for years though because of their skill and understanding. Filtration, such as a protein skimmer, can help as well but IMO shouldn't be relied upon as a means to achieve a higher stocking level. Skimmers fail, and what then? Unless you have an extra humongous skimmer lying around it doesn't sound like a good idea. Actually this goes for all equipment. Try not to be too reliant on your equipment. If you keep a lighter bio-load you'll survive equipment failures much better (in most cases).

C) the requirements of livestock. Ultimately this is what limits us the most IMO. Most marine species are territorial. As the amount of territory diminishes in a tank the aggression rises. As the aggression rises (doesn't even have to be to the point of causing physical harm) the stress rises. As the stress rises fish get weaker and susceptible to disease, and so on. Also remember that you need to feed the fish. The majority of marine fish do best when fed small amounts multiple times per day. We nano-reefers tend to err on the side of feeding too little in an attempt to keep the available nutrients in the water to a minimum. Yet numerous studies have shown that the healthiest fish are fed multiple times per day and this creates a lot of potential waste. Some fish need a lot of rock for foraging. Others need a lot of open water to swim. We as aquarists need to be aware of the natural behaviors of our fish because when we create the proper environment the fish are healthiest and behave naturally.

What about corals? Many corals have a small margin of water quality tolerances. Finally there is your CUC. You need a sufficient CUC for your bio-load.

In conclusion, people on the forums usually give recommendations to beginners that limit the # of fish they put in their tank. Truth is that this is mostly so the beginner can get a "feel" for the hobby and learn how to react quickly. The survival rates of our animals really needs to increase. We need to get rid of the mentality that we can accomplish whatever goals, dreams, or ambitions we have and get back to understanding the biology of the marine ecosystems we try to recreate. We really don't need to know the max bio-load a tank can support. Sorry this probably isn't the answer you wanted to hear, but it's what I've learned through my own trials as well as those of others who share on the forum

lots of info there. where did you find it?

:)

Well worded and thoughtful synopsis...

:)

Thank you! So many times people have jumped down my back(not here though because you all are awesome!) for telling people they can have more or less fish. I seriously want to punch the next person I hear tell a beginner they can have "one inch per gallon". So, you're telling me you can only keep 10 one inch neons in a 10 gallon tank? Pretty dull. Or that you can keep a 10 inch oscar in a ten gallon? Just a little over crowded, I'd think. Anyone know where that "general rule" got started?

lol i know ppl tell me that all the time at the LFS!!!!!!!!
TARDS!

BUMP!
just want ppl to know this info
:)

thought id throw this out their again sinse theirs more and more ppl getting into salt:) enjoy

awesome info right now, I have 3 small damsels, a small tomato clown, small malanarus wrasse, and a small bangaii cardinal in a 25g I wonder what my bio load is.
live rock is around 50-80 pounds.(yes all in a 25g) and I plan to upgrade to a 55g, I wonder how I about doing that with out missing up, if any one can tell me thanks.

WoW o_O............how the hell did you manage to fit all that rock in their?
with that much rock in a 25g their is bound to be little to NO SPACE!!!!
you asking what your bioload is after listing your fish in that tank with all that rock is funny!

the more rock you have in the tank the less water volume.
you have 50-80lbs or rock in a 25g....theirs more LR than water so imm go and guestimate that you total water volume is like 10gallons?????? maybe less????
so with all those fish in a 10g or less water volume is bound to have a HIGH/ HUGE bioload....unless you do WC's every cpl hours or so
even when you upgrade to the 55 consider getting a sump for it!
you can hide all that rock in the sump and not worry bout space in your display