Filter idea: Size and SG of mulm

[elbowdeep88]

Context:

I have been dry for too long now and recently bought a house so am contemplating my dream system. OK so I have actually been spitballing for almost 5 yrs now and am ready to start actually planning. DT probably 150-250 gal. Amongst other things I would love a huge upstream sump/refugium (~100 gal) located a floor above the DT that has a few solenoids to surge water in (without the air). Below the tank would be essentially closed loop: some sort of prefilter (subject of a future post) then a pump up to the second floor.

 

Dilemma:

How to remove mulm and particulates from the system so they do not aggregate in the sump/refugium and make it a massive mulm pit.

 

I do not want consumable media (filter socks) so was thinking of novel ways to remove sediment and centrifugal force came to mind. Turns out a pool filter company is a few steps ahead of me.

 

The Waterco MultiCyclone 16 is a pool filter that forces water through 16 small centrifuges which separates particulate down to about 50 microns as long as they are heavier than water. Then you open a valve and all the particulate just drains out as waste water. That's it.

 

https://www.waterco.us/waterco/brochures/pool-spa/centrifugal-filters/multicyclone-16_zzb1278.pdf

 

https://youtu.be/q_zBUbhxiFI?t=3m53s

https://www.youtube.com/watch?v=twsfUg8ccUg

 

Question:

Mulm settles to the bottom (SG>1) and appears bigger than a human hair is thick (50microns), so it would seem as though the filter would work on these. Certainly on sand. Am I correct here? Does this thing have any chance of working as a primary filter in a reef tank?

Edited October 24, 2017 by elbowdeep88

[Origami]

It should work with particulates, but not dissolved solids or dissolved pollutants. I've read about a tank with settlement boxes that target similar solids in a separate compartment but they rely on gravity and slowed flow to separate the solids rather than centrifugal force. Spinning will require more power and be subject to mechanical failure more than s passive settlement box, and may be more efficient.

 

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[elbowdeep88]

When you say dissolved solids and pollutants, those would be removed by a skimmer right? Any lead on a link to look at the passive option you mention?

 

Anyone hear of someone using centrifugal force in reef filtration?

[Origami]

When you say dissolved solids and pollutants, those would be removed by a skimmer right? Any lead on a link to look at the passive option you mention?

 

Anyone hear of someone using centrifugal force in reef filtration?

 

There have been a few studies on skimmer efficiency and, if I recall, about 35-40% of dissolved organics are removed by skimming. The rest have to be removed by biological processes which, I believe, may result in byproducts that might be removable by skimming. (Recall that the generally accepted theory on how skimmers work is centered around the idea that there are long chain molecules (proteins) that have a hydrophobic end and a hydrophyllic end; and that this causes them to be attracted to air bubbles which, in turn, carries them up and out of the water.) 

 

The settlement box or settling tank concept is one that you'd have to search for. It was probably 10 years or more when I read a build thread (possibly at Reef Central or some other site). It operates on the same principle as settling ponds in water treatment facilities: Water comes in at a rate that is relatively small compared to the volume of the box. You want it to come in smoothly, with a low amount of turbulence. The volume of the box slows the flow through the box down, allowing solids that are denser than water to settle down toward the bottom of the box. Meanwhile, water (less these particulates) overruns the other end of the box. The bottom of the box is then cleaned out from time to time. Sometimes the box has a V or a cone shape, forcing the solids to settle in a concentrated area to make cleaning easier. So look up words like "settlement box" or "settling tank" (be sure to add the word reef or aquarium to the search, too) and go from there. 

 

Filter socks also remove particulates, of course. 

[zygote2k]

Why is mulm an issue enough to get a swirly filter? It seems like an overkill solution for a problem that doesn't really exist.

Some of that mulm and fine particulate silt is actually good for the tank environment as it creates nice cryptic zones. Some will add to the soil mix of the bed that the plants will grow upon in the fuge. Pods love that stuff when seen in the bottom of fuges.

[elbowdeep88]

Why is mulm an issue enough to get a swirly filter? It seems like an overkill solution for a problem that doesn't really exist.

Some of that mulm and fine particulate silt is actually good for the tank environment as it creates nice cryptic zones. Some will add to the soil mix of the bed that the plants will grow upon in the fuge. Pods love that stuff when seen in the bottom of fuges.

It's a fair question and one I go back and forth on for the reasons you mention. The whole point of the large upstream fuge is to capture the benefits of a more natural system with more pods, larger ecosystem, etc. I should mention that the DT will be sparce with rock and won't have sand. Hence the need for a large sump/fuge to hold a ton of rock/sand. I guess that's why i worry about it becoming a big mulm trap, since I don't want to go the sock route.

 

Would you agree that without filter socks, floss, a new whirly filter drum, or something similar, the collection of mulm before a large fuge IS a problem worth solving?

 

 

Plus, with this, I can put a solenoid on the output and automate the flushing and even make that part of an auto water change.

[elbowdeep88]

Thank you both for the insights. As with any novel idea, I am grateful for multiple opinions.

[Origami]

Mulm is detritus, an organic sludge that is heavier than water that settles in the bottoms of our tanks and sumps (wherever there is not enough flow to keep it in suspension). Detritus removal is standard practice for many reefers, whether it's through filter socks, siphoning sand beds, or vacuuming the bottom of our sumps from time to time. It's often loaded with bacteria because it's loaded with nutrients. That's why other life forms (e.g. pods) gravitate toward it - to capture the energy (nutrients) it contains.

 

Some of the best tanks I've seen (namely, Copps' tank) are kept by aquarists who are diligent about capturing and removing detritus. He's got a huge bioload in his tanks, though, so it may be more important for him to remove it. But, as he told us in a talk some time back, detritus control is central to his husbandry approach.

 

Some is probably tolerable, a lot probably not. One can't argue with the fact, though, that if it's not there it won't release nutrients back into the water. It also won't be there for other life to exploit, though. (Some will be as you can never get all of it.)

 

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[zygote2k]

If you put rock in the sump, you will certainly build up detritus under the rock and is therefore not recommended.

 

Surge for the fuge is easily generated by a dump bucket and if constructed correctly, there will be little to no salt creep. This kind of surge is perfect for keeping detritus and other particles in the water column to be removed by mechanical filtration like sponges or mesh.

Edited October 27, 2017 by zygote2k

[Origami]

Elbowdeep88: In your search, I'm curious as to why you are steering clear of filter socks. I don't currently use filter socks. But I do have to empty the sump and clean it out from time to time. I'm thinking about going back to socks (which will require building and adding a filter box) to avoid having to unload the sump.

[elbowdeep88]

I am not married to the idea, but feel there must be a better solution to pretty much anything in this hobby we have been doing for more than 10 years (that said, I also want a turf scrubber). Maybe a better way to say it is using technology to improve upon proven concepts: like how I have used solenoids in the past to create surges-keeping the advantages of the surge, but without the spray created by a carlson or borneman-all because I hate the look of powerheads in tanks-and powerheads chew inverts.

 

1. I am looking for user friendly, effective nutrient export that can be easily customized to increase or decrease the amount of detritus in the system. With a change in programming I can set it to flush daily, weekly, monthly, etc by installing a solenoid on the output.

2. No syphoning and disturbing the fuge. I plan to set up some 5 gal buckets in there full of sand as super deep sand beds. Plus 100-200lbs rock.

3. No consumable media. The maintenence on socks has always grated on my nerves. I set up to clean them on a regular schedule but then look in them and decide "they look fine". The cost to replace adds up, and cleaning them is a chore in my book.

4. Socks may pull out particulates and recently caught mulm, but my suspicion is that mulm in there for more than a few days quickly breaks down and is released into the water due to the flow, significantly reducing their efficacy as a nutrient export device unless one changes them every few days.

 

Thoughts?

I really am just exploring the idea. My biggest hesitations are:

1. Unknown risks inherent in using a device for something it's not really meant to do (fresh vs salt water, indoor vs outdoor use, etc)

2. Simple is often better, and more failproof in this hobby

3. The value goes down appreciatibly in my book if I can't effectively automate the output flushing. Though a quick manual turn of a valve is still better than messing with socks in my book.

Edited October 27, 2017 by elbowdeep88

[Origami]

Thoughts:

 

Filter socks are passive and less prone to failure than components with moving parts. Their maintenance cycle requires that you check them from time to time, so you're more aware of how your system is operating. I'm perfectly, happy, for example that my car uses a passive and not a more complicated centrifugal device to remove carbon and metal fines from the oil in my car. Simple and effective. Easy to maintain. Low, incremental maintenance costs. Cheaper backup (spare filter socks) in case of failure (clogging). 

 

Mulm is, in part, a reaction to debris in the tank. It includes bacteria that colonize after-the-fact. If a filter sock captures the particulates and is periodically cleaned, there's not the same chance for the mulm to develop in the first place. 

 

The ability to turn a valve to dump settled particulates is one of the advantages of a passive settling tank. Sized properly, the settling tank could be part of your water change procedure, dumping a fixed amount of water on each change. You could add filter socks downstream or not. That would be a separate choice that could be implemented later if desired.