Pod Populations

[gemini aquarius(t)]

I have been reading a lot of people talking about feeding mandarins, and I have noticed that there is a common reference to a mandarin being able to consume the amount of pods in a bottle within a day, or less. Then there were people saying that you would need a refugium/sump to be able to produce the amount of pods for a mandarin.. Pretty well-known fact about the sump/fuge. However this got me thinking about how quickly pods would have to reproduce in order for a mandarin to survive in a system where it is eating a "bottle" worth of pods a day.

So I guess my question is, how quickly do pods reproduce. I assume that each species is different, so lets talk averages here.

Thanks

 

[jerpa]

The article I linked below says that many species in our system can go from adult to adult in as little as a few days but as you said each species is different. The importance of the established refugium is that your DT will be fed a constant supply of copepod larvae and adults. Even if the Mandarin eats everything in the tank the refugium still has many viable adults left that are already reproducing. This allows a balance between reproduction and predation to exist that would be difficult to do without a separate predator free area for them to breed. Although a bottle of pods may contain thousands of adults that is a miniscule amount compared to an established refugium. I actually counted the number of pods(mind you this includes isopods, copepods, and amphipods) i could see in one square inch of glass in my refugium. I lost count at 40. So on the front pane only of my 40B refugium I have approximately 23,000 pods.

http://reefkeeping.com/issues/2002-10/rs/index.php

A mandarin strikes every 5-10 seconds of every day. That is 9000-18000 pods a day. Even if they sleep a third of the day that is still 6-12K a day. This is why it is so difficult to keep them without a well established refugium.

 

[gemini aquarius(t)]

Wow! Thanks Jerpa! Very fun read

 

[ReefIsMyMadness]

I had a separate 5 gallon all in one tank in my closet near the display tank that was just for raising copepods and they reproduced quickly as long as you feed them live plankton and crushed fish pellets and give them a 2-3 week head start before you start feeding. I seeded my copepod tank with a bag of 40 and had atleast a 100-150 in three weeks. i had very porous pieces of live rock that i would transfer back forth twice a week that where full of them. My manderan was always happy and couldnt keep up with all the copepods. Since copepods are bigger and more filling then the other types of pods my mandarin would swim past some right in the open he was so full, lol. Also i used the water from my weekly water changes to change the water in my copepods tank. Its actually pretty cool watching them swim and crawl around by the 100's.

Sent from my SGH-T959V using Tapatalk

 

[troyman]

there is always plenty for my mandarin she has a fat little stomach on her she also eats frozen brine shrimp and mysis

 

[norskfisk]

Interesting thing jerpa said. If the pods are 1mm long, 20000 of them corresponds to roughly 5% of a 3 inch fish's weight. So it sounds realistic that a it needs 10K-20K a day.

If you want to test the pod output of your refugium, fill a measuring cup under the return from the refugium and count the number of pods in it. Or hold it several times until at least 10 pods are caught. Multiply/divide up by the flow rate to get the daily output. Combined with the daily need of the fish this will tell you if your refugium pod production, as a real food source for the fish, is just an illusion. Perhaps the real production is going on in the DT. The refugium could still supply algae detritus for the pods to eat though, or smaller animals, eggs. So more complicated microscope techniques may need to be used to give a better evaluation. But I think it will give a good estimate.

 

[Reefin' Dude]

has anybody done the above experiment and actually received pods within a 24 hour period? i ask, because i have done this experiment many times and have asked fellow reefers over the years to run this experiment and so far the answer has been, it just does not happen in any volume that would support any pod eating critter. pods just do not make the trip from live sump to display.

the best way to grow pods is to create farm tanks. a couple of 10g tanks with a HOB filter is all that you need. throw some LR rubble in there and start feeding the tank flake food. the pods will quickly start breeding. just keep doing this until the tank crashes. this is why you have two 10g tanks. the chances of them both crashing is remote. just dip a net into the tank and pull out as many pods as you want to feed the mandarin.

pod populations are indicative of the amount of nutrients in the area. more nutrients more pods.

G~

 

[jerpa]

The adult pods don't have to travel to the DT. The larvae are free swimming and less than 200 microns long. These can then feed corals and other filter feeders and repopulate the DT. I think you would have trouble seeing them in a filter sock unless you went through the detritus with a microscope. It may be anecdotal but I've seen others experience a more robust population after adding a refugium just as I have.

 

[Reefin' Dude]

the reason why people see more pods after adding a live sump is because the live sump increases the total nutrient levels in the system. the more nutrients, the more pods. just like any critter that can self populate in our systems, their limiting factor is the amount of food that is available. knowing that pods come from eutrophic areas, it just makes sense that if you want to increase the pod population, just increase the available nutrients in the system. feed more, or siphon less.

G~

 

[jerpa]

I agree that nutrients could be limiting but I don't see how adding a refugium increases nutrients. It will increase your water volume, and generally adds more rock into the equation but short of feeding more I don't understand where the extra nutrients come from.

 

[Reefin' Dude]

confused? that is what a live sump (refugium) does. it is a slow flow area in which detritus is allowed to settle. that is why macro and pods find it so easy to grow there. this in turn causes eutrophication in the entire system. unless nutrients are removed from the system as fast as they are going in (which is nearly impossible if there are places for detritus to hide anywhere in the system). live sumps are designed exactly for this purpose to increase the nutrient levels in that area, thus the entire system, if not then they would be left empty in order to facilitate detrital removal either by siphon or by skimmer.

G~

 

[ek9vboi]

The adult pods don't have to travel to the DT. The larvae are free swimming and less than 200 microns long. These can then feed corals and other filter feeders and repopulate the DT. I think you would have trouble seeing them in a filter sock unless you went through the detritus with a microscope. It may be anecdotal but I've seen others experience a more robust population after adding a refugium just as I have.

Thank you for this piece of info! I was wondering how the heck it was possible for pods to travel from the fuge/sump to the DT.

Another question, I have a trigger system sump with a separate chamber for the fuge. It's currently being fed via my return which is tee'd off to it. Once the water overflows past that fuge chamber it goes into the section where the water was initially drained into and then going through the bubble trap. Between the bubble trap, there is a sponge... would that be a problem for the pods? Given it's not a 200 micron sock but it prevents micro bubbles from entering the return chamber.

 

[jerpa]

Assuming all livestock are currently present, adding water volume and rock does not increase detritus production. The amount of detritus may be in different areas but it will not increase. In certain situations it could become a nutrient sink but on its own it does nothing to increase nutrients.


A refugium is a place free from predation. That is the only requirement. High flow, low flow, DSB, barebottom, mangroves, chaeto. There as many variations as there are posters on this site. Certain macros love high flow. If i fail to clean my refugium then it is not a flaw in the system. I think a blanket statement that refugiums add nutrients is false. Pods will feed on phytoplankton, algae, and bacterial films as well as detritus. Macroalgae absorbs dissolved nutrients in the water so they have no care for where the detritus is. We tend to bias our lighting towards growing them but they don't grow in the refugium because dissolved nutrient levels are higher there.

 

[jscarlata]

Ever since I put a mystery wrasse in my display, my copepods are either gone or invisible, even in my sump fuge. I have a decent amount of amphiod of all sizes in my overflow as well as fuge, but I never see Copepods. Going to be making an order from reef cleaners next week and plan to get a few bags from them. If that doesn't work I'm going to try and raise them in a separate 5-10g tank and see what happens.

 

[Reefin' Dude]

you are correct adding water volume nor LR does not increase detrital production, assuming of course the LR is not already full of phosphates and the bacteria are not actively creating detritus from the removal of phosphates.

we both know that very few people use the word refugium to mean free of predation. that is why i used the term live sump. people do not put Chaeto in a live sump to keep it from predation, they put it there to keep it out of sight. growing macro just supports my point. if the macro is growing it has nutrients to support it. therefore the system is becoming more eutrophic. it would not be able to live if the nutrient levels are low enough. this all equates to what type of system the aquarist is wanting to emulate. if they are going for an oligotrophic environment, then the ability to grow macro should be considered a bad thing. if they are going for a more eutrophic environment, then being able to grow macro could be what they want, in order to counter the affects of bacterial activity in the system causing pH to drop.

pods absolutely care where the nutrients are. they need to be where the nutrients are in order to live. you have pointed out what they feed on, and as we all know all of those things grow as close to their energy/food source as possible. they do not travel the tank looking for these sources.

how is my statement that a live sump increases the nutrient levels in a system false? does it help in the removal of nutrients? only if something is exported. until that point it is increasing the nutrient levels of the entire system.

G~

 

[jerpa]

The source of nutrients in our tank is primarily food. If my population of "life" is limited by my food additions then adding a refugium will not increase nutrient levels unless I increase feeding. I would argue that if your macroalgae is growing then it is reducing dissolved nutrients in the water. It isnt truly exported unless it is removed but nothing in our tank exports nutrients without some end product being removed. It does however reduce the nutrients available in the water column. Phosphates in rock will contribute to nutrients no matter where it is placed so that is a moot point.

All our tanks accumulate nutrients. We can remove them many ways. Skimming, GFO, carbon dosing, refugiums, and many many more. None of these can add nutrients to the system that weren't put into it in the first place. They may not remove any if run improperly or not maintained. In a poorly maintained refugium the nutrients "trapped" in macroalgae and DSB's can even leach back out. These nutrients were added to the tank through food additions, not because the refugium was installed. I would also agree that certain set-ups could negatively impact other phases of your nutrient export plan but I will never agree that adding a refugium increases nutrients.

But I can agree to disagree

 

[Humuhumunuku]

how is my statement that a live sump increases the nutrient levels in a system false? does it help in the removal of nutrients? only if something is exported. until that point it is increasing the nutrient levels of the entire system.

G~

That is correct, nutrients are only removed if something is exported.
And therefore the opposite must be true. Nutrients are only increasing if something is imported. The only way a live sump would increase nutrients, is if you were intentionally feeding it rather than the tank. Algae growth is a byproduct of eutrophication. The nutrients are there regardless of if you have macro growing or not. The growing macro does not create nutrients unless it is allowed to decay.

Most of the nutrients in our system comes from food we feed our fish or coral. I not aware of anyone increasing their feeding schedule to help their macro grow.

 

[Reefin' Dude]

whether they are dissolved or not is irrelevant. if the nutrients are bound up somewhere in the system whether it is temporarily locked up in a sand bed, GFO, or in macro, the nutrient levels in the entire system have increased. the system has become more eutrophic. that is all that i am saying. therefore adding a live sump does increase the nutrient levels in the entire system. that is what they do. if they were there to increase water volumn, then they would be empty. these nutrient maybe temporarily bound by macro or calcium carbonate, but they are still in the system and have the potential to be released back into the water column. either by stirring the substrate or by the macro dying for some reason. if the detritus is removed before it has a chance to settle into the substrate (impossible) or be taken up by macro, then the system would not become more eutrophic.

this is all about maintaining exports with respect to imports in a timely manner. only the skimmer is able to remove nutrients completely and constantly. everything else just hopefully binds/traps it waiting for us to remember to clean or remove it. until that point the entire system is becoming more eutrophic. bacteria are always at work in our systems. leaving any amount of nutrients around will invite the bacteria to get to work on them. why have anywhere in the system that detritus can settle? why not design the entire system to get detritus to the skimmer? is that not how wild reefs work? are we not trying to emulate the wild reefs?

G~

 

[Humuhumunuku]

whether they are dissolved or not is irrelevant. if the nutrients are bound up somewhere in the system whether it is temporarily locked up in a sand bed, GFO, or in macro, the nutrient levels in the entire system have increased. the system has become more eutrophic. that is all that i am saying. therefore adding a live sump does increase the nutrient levels in the entire system. that is what they do. if they were there to increase water volumn, then they would be empty. these nutrient maybe temporarily bound by macro or calcium carbonate, but they are still in the system and have the potential to be released back into the water column. either by stirring the substrate or by the macro dying for some reason. if the detritus is removed before it has a chance to settle into the substrate (impossible) or be taken up by macro, then the system would not become more eutrophic.

this is all about maintaining exports with respect to imports in a timely manner. only the skimmer is able to remove nutrients completely and constantly. everything else just hopefully binds/traps it waiting for us to remember to clean or remove it. until that point the entire system is becoming more eutrophic. bacteria are always at work in our systems. leaving any amount of nutrients around will invite the bacteria to get to work on them. why have anywhere in the system that detritus can settle? why not design the entire system to get detritus to the skimmer? is that not how wild reefs work? are we not trying to emulate the wild reefs?

G~

I understand what you are saying now, but I think the problem is a general lack of husbandry. If I don't trim my macro and let it die, or allow excess detritus to build up in a sump, that is no different that not cleaning the skimmer out. You still need to actively remove something from the system.

As for the wild, most of what is "removed" from the system happens from it being deposited in the depths somewhere. You often hear "protein skimmers work just like a foamy beach" but very little is actually removed from the system this way. Most of it just ends up breaking down and washing back to sea.

 

[jerpa]

whether they are dissolved or not is irrelevant. if the nutrients are bound up somewhere in the system whether it is temporarily locked up in a sand bed, GFO, or in macro, the nutrient levels in the entire system have increased. the system has become more eutrophic. that is all that i am saying. therefore adding a live sump does increase the nutrient levels in the entire system. that is what they do. if they were there to increase water volumn, then they would be empty. these nutrient maybe temporarily bound by macro or calcium carbonate, but they are still in the system and have the potential to be released back into the water column. either by stirring the substrate or by the macro dying for some reason. if the detritus is removed before it has a chance to settle into the substrate (impossible) or be taken up by macro, then the system would not become more eutrophic.

this is all about maintaining exports with respect to imports in a timely manner. only the skimmer is able to remove nutrients completely and constantly. everything else just hopefully binds/traps it waiting for us to remember to clean or remove it. until that point the entire system is becoming more eutrophic. bacteria are always at work in our systems. leaving any amount of nutrients around will invite the bacteria to get to work on them. why have anywhere in the system that detritus can settle? why not design the entire system to get detritus to the skimmer? is that not how wild reefs work? are we not trying to emulate the wild reefs?

G~

When we speak of nutrient levels in a reef environment we are talking about dissolved nutrients. Nutrients that are bound are not of concern as they are not available to fuel algae growth or inhibit calcification of corals. Following your logic the reefs of the world are huge nutrient sinks due to all the nutrients bound in the life found there.

All our filtration methods simply trap the nutrients. You trim algae, throw away GFO, and empty your skimmate. They all remove available nutrients from the water. We can argue the efficiency of each method but none are adding to the nutrients of our systems.

I love a good debate