# Poret Foam Porosity



## Rhinox (Sep 10, 2009)

I'm going to be purchasing some poret foam for my sump soon. Here is the configuration I'm going with:










That is a 55g sump. They sell the foam in 13x13 sheets at 4" thick, and each side will have 3 of those sheets. In case you're wondering, that will be a volume of about 15gallons of foam, or enough to fill about 4 large canisters.

So my question is, what porosity foam should I get? I penciled into the drawing a 10ppi (blue), then a 20ppi (red), then a 30ppi (black) for filtration getting progressively finer. The sheets are the same price regardless of porosity. Is there any reason I shouldn't use 30ppi sheets the whole way through? Any reason I should just use the 10ppi sheets? Any mix of the 3 better to go with?

obviously, 30ppi will provide finer mechanical filtration and the most surface area for bacteria to colonize, but it will clog more quickly and be a bigger restriction in general. The 10ppi should provide less of a restriction and still more than enough surface area for bacteria (remember, this is 15g of foam). But maybe it won't polish the water as well as I'd like?

What are your thoughts? I should add I intend for this to be the only filtration for the setup. I like to think of it as a very large aquaclear filter. Easy to maintain, just rinse the foam every once in a while and stick it back in. For my 125g tank by the way.

website for reference

Image comparing 10ppi foam to 30ppi foam:


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## Rhinox (Sep 10, 2009)

nobody?

well I guess I'll go with the 10/20/30 on each side. Just wondering if the 30wasn't too fine if I could get better filtration using all 30, or maybe the 30 is way to restrictive and flow wouldn't like to go through and I shoould use all 10 or 20?

I experimented with some open cell foam I found that was used as a packaging materal and when I ran it under the faucet, water did not like to go through it but would rather flow around it. idk how it compares to the poret foam porosity though.


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## FishFlake (Mar 7, 2010)

Have you asked the folks at Swisstropicals?


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## Rhinox (Sep 10, 2009)

FishFlake said:


> Have you asked the folks at Swisstropicals?


you think I'd be so stupid as to not think of that myself???? 

um... 

*runs off to email swisstropicals*

(thanks for the suggestion I actually didn't think to do that )


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## FishFlake (Mar 7, 2010)

Well, I'd didn't think to suggest it until I went to their web site. Let us know what they say.

Did you check out their fish room link? 
:drooling:


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## larry.beck (Jul 31, 2009)

Stephan's a great guy and I'm sure he'll have good, experienced-based advise to give on the best mix. I'm building out my fry and grow-out tanks with Poret and he walked me through a few options on my setup I was considering.


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## t0rns0ul (Dec 27, 2008)

Seems a bit much...

I have a 135g show tank and run two 15g sumps synced with a siphon tube. I purchased one sheet of the 13x13x4", 30ppi which i cut in half to create two 13x6 1/2x4" sheets. I created vertical glass partitions and used each half in each sump sump..

My water is crystal clean and I have a pretty good bio-load with 28 Gibberosa Moba that range from 4-7".. I alternate cleaning each sump poret foam every other month with q simple rinse.

Side note: Be careful about having water drain right onto filter pads.. Any fish that manages past the overflow will get stuck and die there.. When I designed my sumps I wanted to make a safe area of water where fish can stay alive if they go over the overflow and into the sump.

my design. Water enters sump and flows through bubble reducer baffles into the main chamber (area fish can live) then through the poret foam and into the pump chamber. This design has saved the lives of countless fish and shrimp. :thumb:


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## FishFlake (Mar 7, 2010)

Hey Rhinox, what did you decide to do?

I'm designing my first sump build, but I haven't settled on a final design yet.


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## RRasco (Aug 31, 2006)

I have a 4" sheet of 10PPI in my DIY sump and the water is super clean. Much better than when I was just using a prefilter on the overflow. Not to mention the biofilter that has established in there, presumptively.

I don't see why you can't progressively get smaller in PPI. I wouldn't do it based on cost alone, but if you can afford it, I say go for it.

Poret foam is supposed to last a very long time before requiring cleaning. Mine has been in for a month now and I cannot be happier with it.


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## fmueller (Jan 11, 2004)

I filter my 240G with one large sheet of 30ppi PoretÃ‚Â® Foam in the sump as divider. Water comes in on one side of the sump, has to go through the foam, and is pumped out on the other side. That one sheet provides excellent mechanical and biological filtration, and it takes about 6 months for the thing to be loaded up with gunk to the point where it's worth my while to take it out for a good cleaning. For details of the setup click here.

Three sheets of foam as you are planning are serious overkill, and might also reduce the possible flow rate below what you are aiming for. Plus PoretÃ‚Â® Foam ain't cheap. Mind you, it's worth every penny to me, but I wouldn't want to buy more than I need.









_A layer of PoretÃ‚Â® Filter Foam devides this sump container, providing excellent mechanical and biological filtration._


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## FishyOne (Jan 21, 2010)

fmueller said:


> I filter my 240G with one large sheet of 30ppi PoretÃ‚Â® Foam in the sump as divider. Water comes in on one side of the sump, has to go through the foam, and is pumped out on the other side. That one sheet provides excellent mechanical and biological filtration, and it takes about 6 months for the thing to be loaded up with gunk to the point where it's worth my while to take it out for a good cleaning. For details of the setup click here.
> 
> Three sheets of foam as you are planning are serious overkill, and might also reduce the possible flow rate below what you are aiming for. Plus PoretÃ‚Â® Foam ain't cheap. Mind you, it's worth every penny to me, but I wouldn't want to buy more than I need.
> 
> ...


What thickness of Poret did you use? Is it difficult to clean?


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## fmueller (Jan 11, 2004)

FishyOne said:


> What thickness of Poret did you use? Is it difficult to clean?


I bough the sheet at a local fish club meeting here in Ohio at which Stephan Tanner (the man behind Swiss Tropicals) was present. So I had the benefit of some personal consultation. I told him what I wanted to do, and he said: "this is what you need to use", while handing me the sheet. I believe it is the widest and coarsest sheet of foam he has available, since it will do the best job of standing up self supported as divider in a pretty large sump container.

Regarding the cleaning, after 6 months in service, the sheet is fully loaded with debris. I actually have two of the sump containers shown in the picture, and I use two foam sheets, one in each container. The sheets measure roughly 50cm x 50cm (about 20" x 20"). After removing them from the sump, I take them out on the deck and wash them as as good as I can with a garden hose on full blast. I time cleanings so I can do them in the spring and fall. I avoid winter, because during the Ohio winter I can't use my garden hose, and cleaning those large foam sheets inside the house would be very difficult, although somebody might find a way to rinse them in a bathtub.

Stephan Tanner advises not to wring out our squeeze the sheets, but to slap them on a flat surface, because that helps to prevent long term degradation of the foam. Following that advice, I slap the sheets on my wooden deck until no more debris comes out. I use the garden hose to wash the debris from the deck, and I usually make sure that my wife is not around, because she might be grossed out by so much fish poop being washed under our deck. I am sure it is good for the lawn though :lol:


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## RRasco (Aug 31, 2006)

*fmueller*, looks like 10PPI to me, which would be the coarsest and the same I am running. I can snap a picture of my sump tonight. Pretty much the same concept as yours but in an acrylic sump.


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## fmueller (Jan 11, 2004)

Ah yes, if 10ppi is the coarsest, than that's what I have. I wrote 30ppi because I thought that was the coarsest. My bad


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## Rhinox (Sep 10, 2009)

Thanks everyone for the input. It sounds like I may want to reconsider my plans.

I suppose it would VASTLY simplify my project if I didn't have to install baffles in my 55g sump. I was somewhat worried about the downtime while allowing silicone to cure. If I go with the verticle divider sort of idea, then I can probably get them in the sump and get them seeded before I take out the buckets.

Just so we're clear, I intend for this foam to be the sole filtration for the entre tank. I won't have any bio balls or filter socks or polyfill or anything else. You guys are confident that one 4" thick layer of the foam will be enough to do the job? Well, actually, I'll probably go with 1 divider on each side of my sump, similar to the original picture, but with the foam filter divider instead of the baffles on each side. It will be enough?

I'll just need to figure out what ppi to go with. I still intend to send an email out to swiss tropicals, I just haven't got around to it yet.


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## RRasco (Aug 31, 2006)

If you get two pieces, I would try different PPI, like 10 and 20, or 10 and 30. That is, unless you have two overflows and the return goes out the middle - which I'm assuming you do by the sump diagram. In that case, I would use just 10PPI. I have Poret and bio balls in my sump, but the bio balls have been there from the beginning, the Poret is relatively new. It was more a decision not to remove them so much than they are needed, but they certainly don't hurt anything being there. You should be perfectly fine with just PPI for bio filtration, especially if you have two sheets.


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## fmueller (Jan 11, 2004)

Rhinox said:


> I suppose it would VASTLY simplify my project if I didn't have to install baffles in my 55g sump.


One of the deciding factors for me to convert my tank to Poret was precisely that you don't need baffles in the sump. You should definitely take advantage of that feature!



Rhinox said:


> Just so we're clear, I intend for this foam to be the sole filtration for the entire tank. I won't have any bio balls or filter socks or polyfill or anything else. You guys are confident that one 4" thick layer of the foam will be enough to do the job? Well, actually, I'll probably go with 1 divider on each side of my sump, similar to the original picture, but with the foam filter divider instead of the baffles on each side. It will be enough?


Absolutely, no problem at all. That's all I use to filter a heavily stocked 240G, and I consider that to be my best filtered tank. The biofiltration capacity of the foam is huge, and by installing it as a divider you will take full advantage of it. You will have a fairly large surface through which the water can flow. Obviously not all of that surface will have the same flow-through at all times. The areas where most of the water happens to flow through the foam at first will get blocked first. But that doesn't matter, because the water will just find other ways through the foam until it's all loaded up with dirt. That takes a very long time. I believe Stephan Tanner cleans some of his filter mats only once per year. In my case I don't know how long I can go, but after 6 months the water still gets through the foam just fine, and then I clean it. In case it ever does get blocked, I have cut an overflow in the foam.












Rhinox said:


> I'll just need to figure out what ppi to go with.


Go with the coarsest foam and a wide sheet. The foam piece you need as a divider in a 55G is fairly large, and you want it to stand upright unsupported.



Rhinox said:


> I still intend to send an email out to swiss tropicals, I just haven't got around to it yet.


Swiss Tropicals is a one-man show - Stephan Tanner. I only mention it because you give Cleveland as location, but Stephan was a speaker at last year's OCA Extravaganza. You can frequently find him at auctions and other events of fish clubs in our area. He is based in Columbus, OH. You should definitely get in touch with him. Not only is he a nice guy, but you might also be able to buy Poret Foam directly from him at an event and save on shipping. He also tends to run specials at those events :wink:

_Edit: I just found his schedule here:
ALA 2011 Convention Speaker, Workshop & Vendor. Friday-Sunday, Apr 8-10, Cleveland, OH
Excuse the shameless plug, but the American Lifebearer Association (ALA) Convention 2011 takes place in Cleveland, and is organized by the Greater Akron Aquarium Society (GAAS), of which I am a member. It's well worth attending, and if you can pick up some foam on the side, all the better :thumb:_


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## Rhinox (Sep 10, 2009)

Well you guys have me convinced. I've drawn up a new sketch:










I can get two 4" thick sheets (13"x19.5"). Those are just about the right size to divide the 55g tank. There will be about a 1/2" gap between the top of the foam and the bottom of the frame, but the 13" width of the foam is about an inch bigger than the inside width of the tank, so that should be enough friction to hold the foam in place (or I can trim it a little if its too tight). According to the site, thats $40 for each piece of foam, $10 for shipping, so $90 to my door not bad about half the cost of my first idea, not including the cost and time of getting glass cut for baffles and installing them. Glad I started this thread thanks guys for making my project simpler . Just thinking about all that empty space down there at the ends of the sump, I could throw a fish down there if I have to separate them out from the main tank, or maybe even throw some fry in there, or some fast growing plants and have a little refugium. I'm liking this more and more.

I'm still not sure what ppi to get. I know you guys said you have great results with the 10ppi, but all else being equal, wouldn't the 30ppi provide more surface area for bacteria and filter out finer particles at the only expense of clogging faster? I guess since I already am used to rinsing my media at the very least monthly, being able to go a long time without rinsing the foam isn't a big priority to me. Of course, I have to consider that it will be a little more involved to clean the bigger sheet of foam especially in the recommended manner, so I might want to consider being able to make it through the winter without needed to go outside and rinse out the foam.

Another concern I have, do you guys have any issue with Nitrate running away going so long without rinsing the foam? Thats gotta be sucking up a lot of detritus thats not being removed from the system. Do you just do bigger water changes if you need to, or is it really not even a problem?

*fmueller*, thanks for all the information and links! I don't mind the shameless plug, unfortunately I seem to have a hard time making it to events. I actually joined the OCA back in november at the fish swap and I enjoy getting the newsletters, but I haven't been able to make it to a meeting yet, and I missed the extravaganza too... something always seems to come up, and my wife thinks fish clubs are nerdy . So I'll probably just order the foam online and eat the $10 shipping cost which isn't bad at all, but if I can remember and I'm not busy in april I might go check out the Livebearer convention anyways. Don't know anything about livebearers though. Guppies are livebearers, I think... right?  Anyways, maybe I'll think about making a trip down to akron some month to check out a meeting there.


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## BillD (May 17, 2005)

We have a club member who runs 30+ tanks with Hamburg filters, and his preference is for 20 PPI. Some of the tanks have gone a year or more without any maintenance to the foam.


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## Rhinox (Sep 10, 2009)

So I've finally got around to emailing Stephan Tanner. He recommends that I use for each half of the sump one sheet of 20ppi (3" thick), followed by 2 sheets of 30ppi (3" thick), for a total of 9" of foam for the water to pass through on each half of the sump. He also estimates that I'll be able to go longer than a year in between cleanings. Six 3" thick sheets total would cost me $180 for the foam + shipping.

I know there's got to be a conflict of interest here - Stephan I'm sure would love for me to buy as much foam as possible, while I want to get sufficient filtration while spending as little as possible. So, I thought I'd come here to ask you guys your opinion again. I would stuff my sump full of foam if cost wasn't an issue. But at some point, the addition of another sheet of foam won't add enough value to justify the cost. I'm just trying to figure out where that point is.

On one hand, more foam certainly isn't going to provide worse filtration, and in the configuration Stephan recommends, I may never need to disturb whatever bacteria grows in the 30ppi foam sheets for cleaning if the first 20ppi sheet catches most of the detritus.

On the other hand, you guys seems to filter larger tanks than mine with less foam and report that they are your best filtered tanks, and can go for ages without required cleaning.

So now I'm back to the "How much foam do I _really_ need?" question...

And I'm still wondering what happens to all the trapped detritus in the system, what that means as far as nitrate accumulation and water change requirements.


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## Sin in Style2 (Feb 6, 2004)

Rhino its your fault I am now thinking about doing this for my own tank. So i give you this link to help come up with proper sizing of your mats.
http://www.janrigter.nl/mattenfilter/

And this is the formula i curse you with so you can suffer with me lol



> Calculations
> Here are some formula's to do your own calculations:
> A = surface filter mat
> V = flow rate
> ...


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## Rhinox (Sep 10, 2009)

*Sin in Style2*

Now you're talkin my language!! (I am an engineer you know ) Looks exactly like the sort of stuff I can calculate some answer from, rather than just guessing 

Thanks for that info I'll look over it this evening and if you need help understanding the formulas I can walk you through them.


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## Sin in Style2 (Feb 6, 2004)

Thanks, think i got it figured out. 13" Poret block needs like 422gph or somewhere in there. tossed my paper work with all the math done. My mag drive 7 does 460 at 3' so i think im within the range of plenty without being to fast. Ill look at it some more later thought just to much to get done tonight lol thanks for the offer though. Being an engineer i think ill bounce my results off ya when im done to be sure i didnt miss something.

biggest thing is all the math you gotta do before even doing the formulas. US gallons per hour to liters per min to cm per min then you get to do the formulas lol. opcorn:


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## RRasco (Aug 31, 2006)

I would stick with the two 20ppi sheets, based on cost alone. Then again, my dad tells me I'm thrifty. Not to say Stephan is trying to inflate his sales, but you hit it on the head with a conflict of interest. Don't ever ask a salesman how much you need, they'll sell you the moon if you're willing to give them money. Oh that's right, they already sell pieces of the moon!

I can't comment on the nitrates, I don't take measurements as often as I should. I try to just keep up with water changes. So long as the bio-filter is breaking down the organic material, it will be converted to nitrates and removed during WCs. I'm sure our experiences will vary greatly though between different size tanks, poret foam, and flow rates.


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## Rhinox (Sep 10, 2009)

So, I've briefly looked through the link and equations provided by sin in style.

With the equations, someone could in theory use them to determine a foam area size required for a given pump, or a pump size required for a given foam area size.

I don't actually like the way they presented the equations so I'll give my own based on the theory they use.

First, they say the tank should be turned over 1-2 times per hour. So, I have a 125g tank, I should use a pump that provides 125-250 GPH of flow. Lets say I pick 250.

So then, a foam area size is calculated based on the speed (not flow rate) of the water through the foam. They claim the ideal speed of flow through the foam should be 5-10cm/min. Flow rate and area determine speed of flow, so if I say I want 10 cm/min, I can calculate and area needed to get that speed based on a flow of 250gph.

250GPH * 3785cm^3/gal / 60min/hr / 10cm/min = 1577 cm^2 area required, or 245in^2

That is length times width of foam. So, if my sump is 12" wide, then I need 20" deep of water passing through the foam.

If I wanted 1x turnover instead of 2, then I'd only need half the foam area. If I wanted 5cm/min instead of 10, I'd need twice the foam area. etc.

Now, this is definitely NOT whats going on in my tank. I've got a pump producing 1200GPH but its split in 2, so say I've got 2 filters each with 600GPH. That means each filter is turning over the tank about 5 times on their own. More than recommended. Since my sump is fixed and I know it will have about a 12x15 in flow area when its operating, then I can run the calculation in reverse to get the speed of flow through the foam

600GPH * 3785/60 / 180in^2 / 6.45in^2/cm^2 = 33cm/min

Also more than recommended. The article also talks about how when set up as recommended, all the bacterial processes occur in the first half inch of foam. It states that thicker foam or more sheets then are useless for biological filtration. It essentially states that if you're using faster flow rates and multiple sheets of foam, you're creating a horizontal canister filter and not a HMF.

So, what all this means, I'm not too sure. It means that mutiple sheets might not really have that much bacteria in them after all, which means I'd be wasting money on multiple sheets. IF my flow rate was what is recommended. Since it is higher, my sump won't act like a true HMF and will work more like a canister or aquaclear hang on tank filter. For reference, I estimate that the flow speed through an aquaclear 110 is approximately 90-120 cm/min, yet somehow bacteria is able to cultivate the foam just fine there. So I'm not sure I agree with all the theory they're presenting as basis for the 1-2x tank turnover per hour, or 10cm/min through the foam.

What it boils down to for me is I'm going to get 2 20ppi sheets for now, 1 for each side, and see how they work. I can always get more foam later for mechanical filtration if I need it. I would be surprised if the 2 sheets of foam didn't provide me enough bio filtration.

One can go a little crazy worrying about using formulas to make it perfect.


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## Sin in Style2 (Feb 6, 2004)

I think when they speak of bacteria only residing in the first 1/2 inch to 1 inch of foam they are talking about either side of any exposed side. so 1 inch depth would be 2inch thick foam. I think this has something to do with oxygen or flow rate. think it mentions in the article.

Thanks again for the help. according to Rhino i may as well buy another tank for a sump lol. Not sure how tight this formula is but whatever lol. see where it goes.


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## Agridion (Sep 8, 2010)

Rhinox said:


> What it boils down to for me is I'm going to get 2 20ppi sheets for now, 1 for each side, and see how they work. I can always get more foam later for mechanical filtration if I need it. I would be surprised if the 2 sheets of foam didn't provide me enough bio filtration.
> One can go a little crazy worrying about using formulas to make it perfect.


Do you have your Poret sump up and running yet? Did you stick with your plan for having 2 inlets to the sump and one outlet and if so how is that working out for you? Have you had to clean the poret pads at all? I am looking at setting up a sump close to the same way you have drawn and was hoping to hear some good news.

Thanks


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## RRasco (Aug 31, 2006)

I added a few sheets to mine. Now running 4" 10ppi, 2" 20ppi, and 2" 30ppi. I've only cleaned mine once since I put the 4" sheet in January. That was when I changed this tank from a 110 to a 150. Definitely a great media choice! :thumb:


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## BillD (May 17, 2005)

One of our members is into his 4th year of using mattenfilters on all his tanks. He went with the 20ppi, at 2" I believe. His largest tank is a 350 gallon, and the foam has gone a year or more between cleanings. For what you want to do, I would cover the columns with quilt batt material and throw it out whenever it got dirty. That would pretty much eliminate cleaning the sponges.


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## DanniGirl (Jan 25, 2007)

RRasco said:


> I've only cleaned mine once since I put the 4" sheet in January. That was when I changed this tank from a 110 to a 150. *Definitely a great media choice!* :thumb:


Couldn't have said it better myself!
*RRasco*, I have the same, 2" 30ppi in my sump (150 gal tank) and I haven't touched it since February. It was a great investment!


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