measuring bio load

[uscmule]

Hi All,

I'm relatively new to this hobby. I am a software and digital electronic systems engineer by trade, and that tends to color how I look at the world.

I've been cycling some tanks over the last several months (one at a time) and thinking about filters and food and bio-load....  I've noticed that its common for folks in the hobby to decry that there is no good empirical way to measure the load of a tank/fish. But, don't we know the load of every tank implicitly by how much food we are putting in?

In engineering we often call this black box testing... we have no way to measure all of the intricate processes that are going on in various fish, plants, filters, etc.. but, we can measure the inputs and outputs of the system... if we know how much food is going through the system, say per week or per month, and the system is stable, we can measure the load capacity of the system in units of food (grams?). If ammonia/nitrite start increasing with more food (and doesn't stabilize) we could say that the system has reached filter saturation.  If we add raw ammonia (fixed known amount) we could measure how 'reactive' the system is by how long it takes to disappear.

It feels to me like with a little thought and experimentation we could quantify this aspect of the hobby. Whether or not that is desirable, i dont know, but it seems like it would help newbs like me 😉

[Lennie]

It feels kinda impossible to calculate it to me.

Almost all creatures in the tank constantly picks on something or grazes on surfaces. They eat algae and biofilm that the tank offers. So their diet is not limited to offered food only, but they almost always constantly eat something. All tanks offer different amount of natural food growth available based on many factors as everyone has a very unique tank and system really. Even stuff that we cannot test the water for effects growth of many things in the tank. I keep botanicals in my tanks that no way I can calculate the amount consumed by what fish/snail per day. A mystery snail cannot digest food well meanwhile X fish digests it much better, so their poop has different values. Some fish are herbivores, some are omnivores, and some are carnivores. Some eat very messily and some don't make a mess at all!

Also for some creatures, I believe it is very hard to follow a very strict schedule as a fishkeeper. Like as a person who loves snails, my feeding changes every day, sometimes a snello, sometimes a commercial food, but other days just random blanched veggies based on the season!

Also I believe the system of most fish and inverts are different, and when you feed a community tank, it is hard to exactly know which one consumes what amount every time. 

Also, bioload is not really a huge thing in the hobby really. It just helps people to understand some concepts. Like what type of a stock a freshly cycled tank may handle at the beginning. It helps not to be an impulsive buyer, and stocking very slowly so the beneficial bacteria may keep up with the bioload. Also calculation on aqadvisor helps people to not overstock their tanks as newbies, because generally speaking, understocked tanks are much easier to take care of and way more suitable for newbies.

Also stuff like how densely planted your tank is, are the plants fast growers or slow growers, what's your water changing schedule, the size and age of the fish, will constatly change the calculations I assume. As the foods offered also may change based on the age of the fish, even sometimes daily.

 

Also even the size males and females, and even generally the size of the fish from the same species changes a lot. Some are shy eaters, some are crazy feeders.

If you saw one of my female rummy noses and a regular male of mine, you would understand. That female can eat the whole world.

[uscmule]

Hey Lennie, thanks for your thoughts!

Your points about the specifics are exactly what im trying to tackle by using the "black box" paradigm.  All the natural foods in the aquarium ultimately get their nitrogen from the food we feed the fish, no matter if its uneaten or poop. The only real difference is how digestion speeds up the process. So if we measure all the food that goes in, we know the load we are putting on the system. The trick is to measure over a long enough period of time so that the total processing time is covered for digested or uneaten food.

Using a long measuring period also covers some of the interesting variation in feeding schedule.

As for how valuable this is... :shrug: i just noticed a lot of hand-waving on the subject and figured we actually know more than we think we do; this is often how I tackle complex systems in the real world.

[Lennie]

On 3/16/2023 at 10:12 PM, uscmule said:

All the natural foods in the aquarium ultimately get their nitrogen from the food we feed the fish, no matter if its uneaten or poop.

Thats actually hard to tell!

In my case, my tap water has 20 nitrate.

Many people have ammonia/nitrite/nitrate readings in their taps

Also some stuff like silica may result in growth of brown diatoms for example. And fish like otos, borneos or some snails love to eat it.

So every water change may add Nitrogen source to the tank too, so will fertilizers, active substrates, root tabs, etc., or water changes may bring many other things that we don't even know supports what kind of growth!

Also there are many biofilm grazers too besides algae.

 

[uscmule]

Wow... nitrates in the tap? now that you mention it i have heard people say that. In any case, that just gives you a known baseline for nitrate (unless the tap is fluctating wildly?).

SiO2 doesnt have any nitrogen, so diatoms are still getting it from the food, no?