power heads in the fuge

[Octoman]

My DT drain is dropped to the bottom of the fuge. I don't have enough flow coming out of it to really stir the sand/cc on the bottom. I put it lower so that more water would circulate through. When it was close to the top I could see the bubbles come in to the fuge at the top and then fall right over the overflow. Didn't seem like much was staying in there very long.

I added the PH two days ago, the cyano is about half way gone and I've noticed some new growth on the chaeto already.

[framerguy]

Excellent Octo! This thread seemed to produce some good results and actions.

[BigAl07]

I wonder if I need to make changes. I think my chaeto is growing but I wonder if it needs more flow.......

[framerguy]

It's hard to say Al. Flow in the fuge and in the DT is underrated and generally less than needed. It was difficult for me to get used to the amount of flow I have now in the DT but the difference I have noticed in the health of my corals prompted me to look into the flow in the fuge. I had very little in there and the algae was growing very little and slowly. I've only had the two small powerheads in the refugium for a few weeks but have already noticed vast improvement in the health of both the algae and the critters. I have a 55gallon refugium with about 450-500 gph of pass through flow, and two small powerheads with about 150gph each. In my reading it seems that 5-10x flow in the fuge is adequate. Heck, do an experiment...put a powerhead in your fuge and monitor what happens for two weeks. Don't increase the pass through flow, I still believe that dwell time is important, and that is from all the material I have read. Keep us updated no matter what you do!

[cracker]

Originally Posted by framerguy

Excellent Octo! This thread seemed to produce some good results and actions.

Agreed! Great thread. I still have a prob with this concept of "dwell time" Seems to me over a given length of time, the amount of exposure is the same no matter the flow rate in a closed system. I for one like lots of flow.

[framerguy]

Originally Posted by cracker

Agreed! Great thread. I still have a prob with this concept of "dwell time" Seems to me over a given length of time, the amount of exposure is the same no matter the flow rate in a closed system. I for one like lots of flow.

posted by Prow:
no, mainly because of surface skimming from your overflow. the high current in the main tank keeps nasties in the water colum and organics accumulate at the water surface, these get sucked down to the sump, via overflow surface skimming. keeping this water in the refugium longer allows the algae more contact time with this concentrated nutrient rich water. more food in the sump for algae to eat up, faster rates lead to more mixed waters and dilutes whats in the sump so not as much is being removed out of the system in a given time.

It seems that the longer the water is in contact with the algae in the fuge then the more nutrients can be extrapolated from that water. It also seems logical that the faster the water moves through the refugium that less nutrients would be ABLE to be removed because they are escaping through sheer speed. I could be way off base with this thought but it seems logical to me.

[tbittner]

I just had another thought. Faster flow within the tank keeps the nasties in the water column so they can be brought to the sump/fuge. But wouldn't a slow flow through the fuge let those same nasties either sink to the bottom or float across the top of the fuge water?

I guess that's what the pump in the fuge is meant to get around. But in that case, I agree with cracker. Just pump up the flow through the fuge. It all comes in contact with the macro at some point.

[framerguy]

It's a conundrum! And it may not matter, both methods may work. For some reason the rule of the day is slow pass through flow. There may be research to back it up and there may not. If someone knows of a link to that research let's have it.

[prow]

dont know of link.

thanks for quoting that Greg, did not want to say it again

terry your thinking about it wrong. lets ask why not, instead of why

ok this might go into left field a little. say you do have fast flow through the sump/refugium. where would all nutrients end up? they dont stay floating around, they end up behind some rock or somewhere in the back of DT in areas low flow forms because of rock work or whatever. now other algaes, like micros, go to work on it in and grow in the DT.
mmmmm, ok no low flow spots because of rock anywhere, just say, the water is always moving fast everywhere and nothing settles anywhere(not going to happen but just say). so now the nutrients are spread all over evenly so algaes in the DT gets as much nutrients as the macros and skimmer do in the sump. thats not good we want the macros and skimmer to get more so the algae in the DT doesnt grow. fast moving currents suddenly slowed causes nasties to accumulate. we want to maximize the flow in the DT to prevent these areas, however, we do want this to happen in the skimmer and macro areas in the sump. so a sudden low flow in the sump causes a build up of nutrients where we want them

[Octoman]

Prow, I thought that algae in the fuge was taking up dissolved nutrients that won't settle out of the water no matter how slow the water flow is. I didn't think that chaeto could feed off of particulate matter.

[prow]

dissolved nutrients do accumulate, they rise up from sandbes or LR to the water suface, but not limited to it. ever see that layer of film on the surface? many get it in fuge but not the DT bacuse of surface skimming those are orangics. lots of dynamics here.
ok here it is in a nut shell at the water surface ammonia and O2 other organics are plentyful and together with the lights provided energy, phytoplankton/zooplankton use it eat it and attach to things or die sink and get eaten themselves. this make for bigger heavier things, weighing them down until they settle somewhere. keeping higher flow rate in teh DT keeps these things in the water column even though bacteria attach to things and weight them down. in the ocean they accumulate on the bottom in pockets where the flow has taken them. in our tanks more flow in the DT keeps these thing from settling in the DT and keeps them in the water column. thus, surface skimming and less flow in the fuge, allows them to settle in the sump.

here is a link about what i am talking about here. its not about flow in the refugium. its about more about how bacteria, protozoans and things coagulate the organics and things. sorry trying not to get all tech on ya. i think this link will help you get it.
http://drs.nio.org/drs/bitstream/226...ith_chap06.pdf

[Octoman]

Prow, the dynamics you are talking about are accurate and have been heavily researched in the ocean. But that is occuring in a system that is stratified into different layers on the scale of 100 or 1000's of meters. The aggregation of bacteria and particles (the formation of marine snow) happens over time as particles settle to the bottom. This aggregation would never have time to occur in a home aquarium where any digestible particles are snatched up by pods, corals, fish, whatever else can nab them.

Also, even in very large fish tanks, the water is very well mixed from top to bottom (compared to the ocean). The dissolved nutrients are going to stay in the water column until they are taken up by some organism (or precipitated out chemically). What settles out in the sump/fuge is larger particles that have yet to break down such as fecal matter and left over food. What forms the film on top and is skimmed out is hydrophobic organic material. Dissolved nutrients such as nitrates and phosphates are not very effectively removed by a skimmer.

Bacteria can take up nutrients and are vital to the N cycle, but, as you know, they cannot remove NO3 in an oxygenated environment. However, algaes and zooxanthellae can. That is why I have the fuge with chaeto, to remove nitrate and phosphate from the water column.

I think that allowing particles to settle in the fuge or sump only allows them to be broken down and released as more dissolved nutrients into the water. That's why I prefer to use a filter sock to remove the particles before they get there. I don't think that having higher flow or lower flow in the fuge really makes a difference as far as the amount of dissolved nutrients in the water.

[tbittner]

I'm so confused!!!

[prow]

Originally Posted by Octoman

Prow, the dynamics you are talking about are accurate and have been heavily researched in the ocean. But that is occuring in a system that is stratified into different layers on the scale of 100 or 1000's of meters. The aggregation of bacteria and particles (the formation of marine snow) happens over time as particles settle to the bottom. This aggregation would never have time to occur in a home aquarium where any digestible particles are snatched up by pods, corals, fish, whatever else can nab them.

no it does happen in all layers in the water column and yes in our tanks. organic material is light enough to float around. but bacteria/algae and others convert dissolved organics to particulate organic material via by aggregation. this does happen in our tanks, how else do you think the particles get big enough to form detritus, its not because detritus just appears and settles on there own. once detritus is formed its heavy enough to fall out of the water column and settle on the bottom. here is a link showing it does occur in our tanks. it has many ref. in case you want proof. the link here is only part 6, but links to 1-7 are provided aswell. glad i found this link, this is the link i was looking for before. it covers everthing we have been talking about and them some on the nutrients that is. The Food of Reefs, Part 6: Particulate Organic Matter by Eric Borneman - Reefkeeping.com

Also, even in very large fish tanks, the water is very well mixed from top to bottom (compared to the ocean). The dissolved nutrients are going to stay in the water column until they are taken up by some organism (or precipitated out chemically). What settles out in the sump/fuge is larger particles that have yet to break down such as fecal matter and left over food. What forms the film on top and is skimmed out is hydrophobic organic material. Dissolved nutrients such as nitrates and phosphates are not very effectively removed by a skimmer.

not ture, the water in our tanks is not very mixed. there are a few studies that show this, the link i gave above does go into it. but, you can see how our tanks are not very mixed just by algae growths. algae will grow in the most nutrient rich areas, many see this on there sandbeds or rock work. check the link it goes into some details on this.

Bacteria can take up nutrients and are vital to the N cycle, but, as you know, they cannot remove NO3 in an oxygenated environment. However, algaes and zooxanthellae can. That is why I have the fuge with chaeto, to remove nitrate and phosphate from the water column.

sure they can, facultative bacteria do and lets not forget about bacteria with the sulfer cycle ture bacteria with the nitrogen cycle can not, but there is more than just the nitrogen cycle going on.

I think that allowing particles to settle in the fuge or sump only allows them to be broken down and released as more dissolved nutrients into the water. That's why I prefer to use a filter sock to remove the particles before they get there. I don't think that having higher flow or lower flow in the fuge really makes a difference as far as the amount of dissolved nutrients in the water.

i disagree.

FYI using your filter sock is a paradox and can do more harm than good, the link goes into this also

[Octoman]

First of all, I would like to say thanks for the friendly debate. This is one of the thins I love about RS, people seem to keep their cool and can be mature when they disagree about things.

And great link! I'll have to read all the parts in that series...

Originally Posted by prow

no it does happen in all layers in the water column and yes in our tanks. organic material is light enough to float around. but bacteria/algae and others convert dissolved organics to particulate organic material via by aggregation. this does happen in our tanks, how else do you think the particles get big enough to form detritus, its not because detritus just appears and settles on there own. once detritus is formed its heavy enough to fall out of the water column and settle on the bottom.

In your cited article he states that "Bacteria can even convert dissolved organic material (DOM) into particulate organic material (POM) by aggregating it in the presence of carbon." However he also states that the primary source of POM is "fish feces, coral mucus, algal remnants, worm castings and burrowings, the molts of small crustaceans, uneaten food, and other debris". This suggests to me that bacterial flocculation is a minor component of the source of POM. However, I will concede that it can exist in the tank.

Originally Posted by prow

not ture, the water in our tanks is not very mixed. there are a few studies that show this, the link i gave above does go into it. but, you can see how our tanks are not very mixed just by algae growths. algae will grow in the most nutrient rich areas, many see this on there sandbeds or rock work. check the link it goes into some details on this.

Our water is extremely well mixed when compared to the ocean, here is a typical nitrate profile for water in the open ocean...



I just used nitrate as an example, but profiles with large variation can be applied to salinity, temperature, density, and many other chemicals. Comparatively, our tanks are very well mixed. Even a small amount of flow mixes the water column from top to bottom very easily. However, we may be talking about different things, if you are including the water trapped in the sand bed or rock, then I would agree that this water is very different from the water in that is flowing throughout the tank.

That said, I always try to be open-minded and I would be very interested to see the studies you have referenced if you can find them.

Originally Posted by prow

sure they can, facultative bacteria do and lets not forget about bacteria with the sulfer cycle ture bacteria with the nitrogen cycle can not, but there is more than just the nitrogen cycle going on.

There are many microbial processes at work such as nitrification, denitrification, sulfate reduction, iron and manganese reduction just to name a few. My point was that macroalgae in the fuge can be very effective at removing dissolved nitrate and phosphate, and can do so in an aerobic environment.

Originally Posted by prow

FYI using your filter sock is a paradox and can do more harm than good, the link goes into this also

Ok, your link has convinced me on the filter sock and mine will be coming off.