Lets Talk About ~Filtration Concepts~

[mojoreef]

I thought we could use this discussion to break down the various concepts of filtration employed in the keeping of a reef tank. There are a few main filtration concepts, i.e.: deep sand beds, shallow sand beds, bare bottom systems, and miracle mud systems. Let's break them down to understand how they work and discuss what is necessary in order to set them up properly, maintain them properly, and some of the pros and cons that come with each system. Let's not make this a which systems better type of thread, but instead an analysis of how each system works. That way folks can understand what is involved in each system and what to expect in both good and bad things that may happen throughout their tanks lifespan. With this knowledge folks can make an educated choice on the system they may want to employ.
Let's take one system at a time, I will write up an explanation of the system and then we can break it down and talk about it. Then we'll go to the next system.


Mike

 

[Montanarocknreefer]

I'm ready!

 

[mojoreef]

OK let's start with bare bottom systems. The concept of a bare bottom system is to utilize detritus/waste/left over food and then to remove it from the system prior to the breakdown and reduction of its through bacterial processes. The BB system employees properly positioned water flow in order to keep the above suspended in the water column. With it being suspended in the water column this allows the detritus/waste/extra food to be available continuously for the corals and creatures that may require it. It is then removed from the system through the tanks overflow system and sent to a strong protein skimmer and other miscellaneous equipment (if chosen) to ultimately be removed completely.
Using this system one must employ good flow directed towards the bottom of the tank, this will keep the vast majority of the above from settling on the bottom. It will not keep 100% of it from doing so, so the user must use a powerhead or a turkey baster to periodically blow off the rocks and the areas where it might still be collecting. In my opinion your skimmer on this kind of system should be run very wet in order to remove as much solid material as possible. The live rock in this system, although it does not have the same amount of capability of denitrification as say a deep sand bed would, it is more than enough to accomplish what little is needed.
Pros:
Will not allow for the buildup of non-nitrogen based products as a DSB will.
Allows for a better water flow system that is required when trying to mimic high-energy reef systems.
Allows for better distribution of detritus/waste/left over food to the entire tank system, instead of only feeding the creatures in the substrate.
With the removal of the above your getting positive exportation of nutrients that are introduced to the tank via feeding/waste/and the organics that are usually associated with them.
Cons:
With running the skimmer wet you will removed some of the beneficial planktonic creatures that happened to run through the skimmer. Larger creatures such of the size of pods and on will not be harmed.
This system does not have the same capacity for the processes of denitrification as a deep sand bed system has.
You will not get the same numbers of planktonic life (Larva, newkton, protzoa) as you will get with a deep sand bed or shallow sand bed system. However you will still get decent amount of it. You will also still see good amounts of pod and worm populations.


well let's talk about this one for a bit.


mike

 

[Sgt.Baker]

nice thread.
do pods/worms etc have the ability to find the food particles suspended? or only filter feeders? i imagine there still has to be some dead spots in crevasses where these small animals could find their lunch.

i think one disadvantage would be a more rigorous maintenance schedule to perform the removal of this waste...but advantageously removal of detritus is easier and more concentrated than a routine water change on a sand bed tank.

would alternating times with a powerfilter and mechanical filtration a couple times a week for a few hours and then removal and cleaning of the mechanical media be a good incorporation into this type of system?

 

[fishermann]

Good thread Mike i have had bear bottom for almost two years now in both my glass tanks, ever since i got back into the hobby. If i knew then what i know now i would have had them drilled to run a spray bar across the bottom back. Well i didn't so i just take a hose and vac my bottom off 2 or 3 times a week, takes 10 mins. I run the hose into the 100 micron bag that is in the sump which the 2 hoses from the tank overflow runs into, it catches alot of detritus which helps the skimmer. I change it out 2 or 3 times a week so as not to let the detritus break down much further. On the smaller 60gal i have nothing but softies, mushrooms, and some other lps and the mushrooms and everything seem to be getting plenty of food since they are huge and i don't supplement feed anything. The bb system may be a tad more maintance, course i don't have fine sand blowing around, but i think in the LONG run i well be happier, sure wish i had SPRAY BARS though. John

 

[Sgt.Baker]

doesn't the 100micron bag remove the "food" for the corals?
i know yours are doing great, but i thought part of this concept was to keep stuff in suspension.

 

[fishermann]

Several people and systems i have talked to and seen that impressed me have used these felt bags. They come with the berlin sumps that marine depot sells. I had the same question when i first started using them, but alot of people use filter floss or sponges and these allow me to vac the tank without taking out tank water, so i kept an eye on the sps's in the 75 and the stuff in the 60 and everything actually seemed to perk up a little and that has been for over a year now. I get my bags from The Shark Reef, one of our sponsors. He is the one who conviced me to try it, he uses the same. I believe there is no problem having enough food for the corals.

 

[Scooterman]

I always wondered about the limitation of this type of system, like can you do a nano cube with BB? If so, do you have to change some of the things required to keep it going like in a full(average sized) reef? How about water changes, do you need to do as much as in a DSB or other type system? The hardest part of this types set-up, is it determining how many fish you can keep, corals etc or can you keep as much as in a DSB? Do I need hermits, snails etc or can I keep it clean and simple or maybe I like lots of crabs & snails, do these affect the system? Where you say water flow, what do you mean by that, tons of PH's all over the place, spray bars, just how do I determine what is enough, is there a formula for a sps,lps etc? If the skimmer suck out so much, do I need to feed tank to replace what I take out.

 

[fishermann]

scooterman alot of questions, i well give you my thoughts, and i'm sure there well be others. I believe if you want to have a high bio load a bb system is the only way to go. I have a high bio load with big fish for my size tanks. My believe is you can keep the detritus from overloading the tank with bad things {detritus, bacteria, algae food and so on} by removing it before it feeds all the bad things and believe me their is plenty left over to feed the corals, soft or hard. I have just a normal amount of ph's in the tank to keep from having dead spots. I do wish i had spray bars like mike has down low to blow from back to front across the bottom. I don't neccessarly think i need the suspension for feeding the corals but it would help keep things suspended for removal better so i wouldn't have to vac quite as often, but it is not that big of a problem as to teat everything down to add spray bars. I have snails and hermits to help keep the rock clean, plus i just like having them, i would say they are nomore needed with then with a dsb,just personal preference. As i posted above i don't feed any food other then what i feed the fish and i have mushrooms and stars and they are large and doing fine for 2 yrs now. John

 

[DonW]

Fisherman,

Are you using the bags as a vacuum bag and returning the water to your sump??

What if any filtering abilities does the coralline on the floor have.

Don

 

[fishermann]

Don i have a bag in each of my sumps that the lines from my overflows run into, you can get the idea if you look at marine depots berlin sumps pictures. I don't use the bags with the plastic rings, i use the bags with no rings and they are bigger. When i am going to change a bag out every couple days i take my vac hose and put the end down in the bag to vac the floor of the tank, so i don't have to do a water change everytime i vac the bottom. I asked mike a question similar to yours, only if he thought the corralline might hide some detritus, but we didn't think enough to matter. John

 

[mojoreef]

Wow, I thought this might raise some questions:lol:
Sgt.Baker

do pods/worms etc have the ability to find the food particles suspended? or only filter feeders? i imagine there still has to be some dead spots in crevasses where these small animals could find their lunch.

the matter what kind of flow you have, or how good it is your always get it get areas where detritus and such will land. Most the time as with all types of tanks it will land on an in the various crevices and indentations in your live rock. The advantage would be if a piece of the above is if the detritus missed landing on the live rock instead of it being consumed by us and substrate critter it would be blown backup and have a chance of landing back on the live rock or in an area where the pods would have a second crack at it.

i think one disadvantage would be a more rigorous maintenance schedule to perform the removal of this waste...but advantageously removal of detritus is easier and more concentrated than a routine water change on a sand bed tank.

I don't know if I would call it a rigorous maintenance schedule. I give my rocks and build up areas a quick blow with a powerhead once every couple weeks. Clean the skimmer about once a week but that's about it. Water changes don't really do anything for what's concentrating in a sand bed but let's leave that one alone until we come up to the deep sand bed filtration concept.

would alternating times with a powerfilter and mechanical filtration a couple times a week for a few hours and then removal and cleaning of the mechanical media be a good incorporation into this type of system?

it might be I run a carbon filter once a month for about two or three days but I don't think the mechanical filter is required. A good skimmer should take care of things for you. But your always open to other devices such as the UV sterilizer, ozone generator and so on.

doesn't the 100micron bag remove the "food" for the corals?

you bet it does, on my tank when I decide to put up fell bag on its a 5 micron. Yes the concept is to keep the detritus and so on in suspension but not indefinitely you alternately want to get it out of the tank before bacteria begin to reduce and rot it. So if you can keep it in suspension for a few hours and then remove it you have accomplished what you want to do. Consider it like serving dinner and then cleaning it out after you're finished. Later on, and/or tomorrow we will serve a whole other fresh dinner and then clean up after it to.

 

[mojoreef]

Gee Scott feel free to ask a question or two :lol:

I always wondered about the limitation of this type of system, like can you do a nano cube with BB? If so, do you have to change some of the things required to keep it going like in a full(average sized) reef? How about water changes, do you need to do as much as in a DSB or other type system?

I don't see why you couldn't do any type of tank with this type of system. As per water changes, you would do them as often as you wish I guess. It would depend on what you were doing the water changes for? If you're doing water changes to replenish elements, that he would do them as much is required. If you are do a water changes to dilute pollution, that is the concept I have never understood. I always thought it would be better to remove the source of pollution (detritus and so on) then it would be to just diluted????? On the DSB part of that question at that again what we get to them.

The hardest part of this types set-up, is it determining how many fish you can keep, corals etc or can you keep as much as in a DSB?

see this is kind of myth. You really have to think about this one Scott. In a DSB type system your cycling/sinking/exporting is limited by how much bioload the sand substrate can handle. According to the experts that bioload is very low. On a BB system your restricted by the effectiveness of your filtration. You can load the tank up with as many creatures as you can have effective exportation of their waste/detritus/extra food. An example of this would be John Saxby, he has a large thousand gallon tank, but he has over 500 fish in it. The only way he can do this is by having a system that effectively deals with the detritus/waste/left over food.

Do I need hermits, snails etc or can I keep it clean and simple or maybe I like lots of crabs & snails, do these affect the system?

you can keep these creatures if you want, I have a bunch of my tank. They will eat algae and so on but they aren't going to get rid of it, they're just going to cycle it. Many people think that snails, crabs, stars, worms, pods and so on are a means of export for algae and nutrients. They aren't. They are merely one stage in the cycling of nutrients, unless of course you remove them from the tank after a while, then it could be considered exportation. These critters simply consumed various products and poop out 90% of what they just ingested. Yes they do use about 10% for their energy budget and growth, but eventually they will die in your tank and everything that they have consumed over what ever. Of time will be put right back into the system. The nutrients cycle.

Where you say water flow, what do you mean by that, tons of PH's all over the place, spray bars, just how do I determine what is enough, is there a formula for a sps,lps etc? If the skimmer suck out so much, do I need to feed tank to replace what I take out.

water flow could be achieved in many different ways, powerheads, closed loops, spray bars or what ever. The concept is simply to not allow the detritus/waste/left over food to sit on the bottom of the tank and rot. So when you do design your flow just keep that in mind..


mike

 

[szidls]

you bet it does, on my tank when I decide to put up fell bag on its a 5 micron. Yes the concept is to keep the detritus and so on in suspension but not indefinitely you alternately want to get it out of the tank before bacteria begin to reduce and rot it. So if you can keep it in suspension for a few hours and then remove it you have accomplished what you want to do. Consider it like serving dinner and then cleaning it out after you're finished. Later on, and/or tomorrow we will serve a whole other fresh dinner and then clean up after it to.

So Mike are you saying that you put a micron bag on intermittently? Say on for a day and off for a day? If you are using live rock rubble in your sump should the detritus be cleaned by additional agitation with a power head on the same scedual as regular tank maintenence? Scott

 

[clownnrnd]

Had to jump in on this one . Looks as if it is cooking up to be a very informative thread. Thanks Mojo
I used to have 90gal. FOWLR system that I ran w/ a barebottom. As stated earlier I think a spray bar along the bottom is very important as it helps eliminate dead spots and aids in getting detritus back up into the water column where it can be used as food.
once a week or so I would take a hose and start a siphon from the tank to the sump and run it through a filter bag to remove any of the accumulations.
See Ya

 

[mojoreef]

So Mike are you saying that you put a micron bag on intermittently? Say on for a day and off for a day? If you are using live rock rubble in your sump should the detritus be cleaned by additional agitation with a power head on the same scedual as regular tank maintenence? Scott

Scott every system is different and has different circumstances. On my system there is a slow build up of detritus in the water column over the course of three weeks or so. At that point I will put a filter stock on the drain lines for a couple of days and run the carbon. Then I take it off and wait another few weeks, it's not really a carved in stone schedule just whenever I think I want to remove it all.
I don't keep any rubble in my sump, but the sump will still act as they settling tank for detritus. I use a diatom filter to suck the detritus out, sometimes in the main tank I will use that diatom filter instead of a power head, it all depends on how lazy I am. LOL

 

[jks1]

I guess Im filter bag challenged. I have run the type that marine depot sells for their berlin sumps. After a few days it needs to be cleaned. I tried urning it inside out and rinsing it thouroghly in warm/hot water, this removes big particles, but not the small stuff ingrained in the bag. If I stick the same sock back in the tank it will clog and overflow the top in a very short time. What am I doing wrong here?

This is a great thread- although I dont have a BB, it will be a great referrence to see the pro's and con's of each..

 

[NaH2O]

There has been so much information on phosphates lately, and their role in algal growth. Since a BB system doesn't have a way to sink phosphates, is it necessary to always have something like Rowaphos, for example, on the system? I know there are ways to try and limit the phosphates that are introduced, but it seems there will always be an issue, unless you have something in place to remove them.

 

[mojoreef]

John I only use mine for that couple day period, when I am done I just take a garden hose to it. If the wife isnt watching I will through it into the washer, lol

Nikki Good question. But what it comes to input a BB tank has just as much as any other tank system. You really have to keep in mind what phosphates are associated with. Part of the phosphate cycle is animal, i.e.: bacteria. Where there is detritus/waste/food there will be bacteria of all kinds shapes and forms, this includes nitrifying bacteria and denitrifying bacteria, when the detritus and so on is removed from the tank it also removes the organic phosphate that is associated with it. Running a phosphate remover as far as I'm concerned is always an excellent option regardless of what style system you run. What it will allow is that any inorganic phosphate that enters the tank or is produced by the tank will be taken out by it. Always a nice weapon to have on hand in the fight again just phosphate.

 

[Stircrazy]

If the wife isnt watching I will through it into the washer, lol
.

your a brave man....

Steve