Filtration Thoughts

[davelin315]

I have been thinking a lot about filtration lately and there were some topics I wanted to bring up for thoughtful discussion.

 

First, an interesting side note to the carbon discussion in another post, I recently toured a metropolitan water facility for producing drinking water and in their sand filters the industry standard seems to be to use activated carbon as the top layer and then to leave it in place for 10-15 years with constant backwashing. I asked about the useful life for the carbon as I knew it would be exhausted very quickly and they said that its abilities to remove impurities was not the driving factor behind its use but that its porosity and micro structure allowed for it to be a superior source of biological filtration over just about anything else. They felt that it would not release anything once it was tapped out in terms of removal of impurities and that this would instead allow for it to be a far more effective filter overall. By the way, this is apparently how all of the drinking water for Fairfax and Loudoun Counties is produced, including at the new Loudoun facility being built right now. This has made me curious as to whether very gently tumbled carbon (or at least carbon that is receiving mechanically "pure" water exposure) could be a great biological filter even after its useful life as a chemical filter is exhausted.

 

The second one is on mechanical filtration of water in our systems and how it affects longevity of our animals. I was following a FB post by someone using the the new CoralVue (I think) Klir filter system and the use of fleece or whatever material it incorporates on its rolls to replace filter socks and it got me thinking - do we introduce a lot of microplastics into our systems through the use of various filter materials? If we do, and a brief analysis of what can produce microplastics against what we use in our tanks leads me to assume that we do, how does this affect the life in our tanks? There are obvious things that do not occur in our systems that would reduce the ingestion of these plastics by our animals such as a lack of predation up to an apex predator and the lack of floating plastic garbage in our tanks, but if we are possibly introducing microplastics into our systems through the use of plastic equipment in circulation and filtration are we shortening the lives of our animals? Could it be that some of the mysterious deaths of what appear to be healthy animals over time might be attributed to ingestion of microplastics? Curious about this one and don't feel that I have a ready assumption as to whether this is actually a problem or not. Wondering if anyone has the ability to microanalyze tank water for the presence of microplastics across a large sample...

[Origami]

I can't say much about the microplastics thing, but I will say that just a couple of months ago, I removed a whole-house carbon filter from my well closet. The thing was over four feet tall and about 10 inches around. It was made to last for years. Anyway, I removed it because I was afraid that it had the potential to be, was, or could be a home for bacteria. On city water systems, it would do alright. On a well, though, I figured that there was nothing that would prevent bacteria from colonizing the GAC bed.

 

We use GAC for different reasons in our tanks - specifically to remove gelbstoff (yellow organics). It sounds like Fairfax and Loudoun are using it differently. It might be an interesting use of depleted GAC in our tanks, though.

[paul b]

I feel that depleted carbon would be a wonderful material for housing bacteria if that is what you are looking for.  I used carbon for decades but no longer use it because I think it removes beneficial things as well as detrimental things, but if I depleted it someplace else, Like for instance in Tom's house,   then I may use it in my tank.  It would provide massive area for bacteria that you could use if you don't have enough rock to provide that area such as a holding or temporary tank.

I think almost any show tank will house enough rock and substrait to grow enough bacteria for our needs. 

Sewage treatment facilities have much bigger problems and need to shrink their footprint. 

 

As for microplastics, I don't think that is a big problem with fish.  They have a very simple digestive system and almost anything they eat, will be easily expelled.  In the sea they eat fish every day and those "micro" bones (which don't dissolve completely ) have no problems passing through them.

I guess we could feed ping pong balls to some tuna to see if they come out.  If they do, I don't want to play ping pong with them.   

Edited August 20, 2017 by paul b

[davelin315]

Actually, Paul, I brought up the microplastics because lately I have seen studies that show fish dying off because of impaction in their digestive systems that is almost wholely plastic.  It's a gradual buildup and seems to be similar to what is experienced with heavy metals like mercury.  Not sure how accurate these studies are but they are out there.

[paul b]

I "think" those plastics that are impacting fishes stomach's are not really Micro plastics. I have seen pictures of what you are talking about and I can clearly see that plastic as it is not really "micro" But I guess it is what you are describing Micro as.

[Origami]

Actually, Paul, I brought up the microplastics because lately I have seen studies that show fish dying off because of impaction in their digestive systems that is almost wholely plastic.  It's a gradual buildup and seems to be similar to what is experienced with heavy metals like mercury.  Not sure how accurate these studies are but they are out there.

 

 

I "think" those plastics that are impacting fishes stomach's are not really Micro plastics. I have seen pictures of what you are talking about and I can clearly see that plastic as it is not really "micro" But I guess it is what you are describing Micro as.

 

Agreed. The "microplastics" that I've seen referred to in news articles are actually small particles (some as small as a grain of sand) that result from larger pieces being ground down into smaller particles by the effect of sun and wave action. Impaction would be a different (physical) mechanism (resulting in something like constipation) from ingestion/digestion which is more like what happens with mercury when it makes its way into the tissues of the animal. I don't think that anybody has said anything yet about possible effects of digesting plastics or if that's happening.

[paul b]

Think of it as fiber in their diet.  OK, Maybe not

[davelin315]

Think of it as fiber in their diet.  OK, Maybe not

[Rob A]

For a while now there have been those little tiny plastic pellets in some hand soaps that I believe have just recently been outlawed. I assume those things have also been gumming up fish and critters in oceans and rivers? I don't know if the pellets can make it back into the water supply but hopefully an RO unit would filter those out.

[davelin315]

RO would definitely filter all of that out as the pores in the various filters are absolutely tiny.  You should not be getting much above .0001 micron particulate matter unless it is from the DI resin itself as the RO membrane filters to .0001 micron.

[Origami]

RO would definitely filter all of that out as the pores in the various filters are absolutely tiny.  You should not be getting much above .0001 micron particulate matter unless it is from the DI resin itself as the RO membrane filters to .0001 micron.

Not to mention that there's normally a pretty good sediment filter in front of all the stages. Pore sizes range from  a half-micron to 20 microns, typically. 

[paul b]

Fish eat gravel and sand all the time with no problems.  Ever see a sea ray eat a crab?  It eats more sand then crab and they don't seem to have problems

[sen5241b]

Interesting. On the small scale that we use carbon in  our tanks, its cheap enough that we can change it out frequently. I have heard stories of people removing some media (like bioballs) holding beneficial bacteria and then a cycle ensuing but I don't use enough carbon for that to be a problem.