Poret Decay

[Midwater]

Poret foam is the media of the first chamber of my sumps. Specifically, water goes though one layer of floss, half a dozen odd layers of poret, and then an awful lot of pumice, which is the main biological media. I change the floss every couple of days here or there, and once per week, I take out all the poret, rinse it and leave it to dry in the sun. I have a second set of poret cut to the same size, so I alternate each week.

But I have noticed recently that the poret is decaying. At least the surface appears to be decaying, with bits of the black foam coming loose after each drying, and cracks appearing in the structure.

I thought poret lasted for years. My current batch is about eighteen months old, and so with alternation has been used for about nine months. Much of the pumice I have got has been in constant use for more that twenty years.

Is it decaying because I dry it in the sun? I do live in a very hot environment. I do know that UV can damage many plastics.

Has anyone else noticed poret decay? How long should it last? Are there different grades of poret? Should I stop drying it? How in general should I care for poret, apart from what I am already doing?

 

[esoxlucius]

Yes, if there isn't any UV stabilizers in the plastic then drying them out weekly in the sun is going to degrade the polymer structure more quickly. And I think I can pretty much guarantee that there isn't any UV stabilizers in there simply because they're only added to plastics if the end use is predominantly outside, and poret foam isn't!

If your filter floss is your primary catchment area for gunk, and as long as you keep on top of replacing it, which you do, I see no real reason to clean your poret foam weekly anyway. Leave it longer. Less cleaning and subsequent minimal drying time in the sun should improve your situation no end.

 

[duanes]

I first added my current 2" Porret block, wall in the sump, back Dec of 2020.

I hose it down, but put it back wet, and have not noticed any deterioration in those 2 years 9 months.
From what I also understand, direct UV can cause it to break down (just like it does a Neoprene dive suit.
I am also a bit lazy about hosing it down though, and rinse it only about once a month, because in the sump there is a population of shrimp that keep the detritus minimal, and do a little cleaning for me.

Because the Porret is the lesser part of my filtration (plants being the most predominant) I theorize the shrimp help break down the detritus further, making the by-product more available to the plants.

Efluent from the main tank, enters the 125 gal sump om the right end, and must pass thru all the plants and shrimp, before it hits the Porrett Foam, and a couple small bags of bio-media on the left.

 

[jjohnwm]

I use a lot of this stuff; when I moved to this province in 2011 I brought with me four mature Poret foam filters, and some of them were at least 5 or 6 years old then. All are still in service. Those blocks are stand-alone filters, but I have also used it for Mattenfilters and as sheets or layers in large DIY filter boxes or sumps.

Once I incorporate Poret into a filter, that's it; I never intentionally let it dry out again. The bacterial colony is too valuable to let it go to waste. Even in filters where the primary biofiltration is handled by some other medium and the Poret is mainly mechanical, I try not to kill off the bacteria. Cleaning of the Mattenfilters and sponge blocks is done outside with a high-pressure hose in the warm weather, and in the fishroom laundry tub during the cold. I just blast the thing with cold water until the water runs off mostly clear; if you try to get it 100% clean you will grow old and die waiting for that to happen. Unsupported sheets are helped along by squeezing and manipulating; the stand-alone blocks are attached with silicone to 6x6 ceramic tile bases, and are cleaned strictly by hosing. Cleaning might be every couple days or even daily in the case of mech-filtration sheets, or every couple months for large sponge blocks, or maybe yearly for large Mattens. I vacuum the surface of those regularly to remove as much dirt as I can.

The sheets I use for mechanical filtration and pre-filtration have been hosed, squeezed and replaced many hundreds of times, possible into the 4-digit range, and they're still great.

I think maybe twice in the past 15 years I have disinfected a couple of individual blocks of Poret due to disease concerns. I soaked in bleach, rinsed well, air-dried (just air, not sitting in the sun) and all was good.

The key point is that all my Poret is old, it never sees sunshine for more than a couple minutes, it virtually never dries out, it endures a fair bit of manhandling and physical abuse...and it is all in good, solid condition, with no deterioration of any kind. A fair percentage of it is older than many of the members posting on MFK are. So I think that Esox's assessment above is correct; the sun-drying sounds like the kiss of death for your Poret.

 

[FINWIN]

I just ordered more Poret foam the other day....going to try sandwiching the 40ppi with the 20ppi. I'm noticing decay too. The outer layers are starting to crumble in small chunks though the middle part stays intact. Almost like its dry rot. I might start rotating pieces to see if that solves the problem.

 

[jjohnwm]

I just ordered more Poret foam the other day....going to try sandwiching the 40ppi with the 20ppi. I'm noticing decay too. The outer layers are starting to crumble in small chunks though the middle part stays intact. Almost like its dry rot. I might start rotating pieces to see if that solves the problem.

Do you sun dry yours? Dry it out a lot? This is a bit disturbing to hear.

I love this product...and I really, really hope that they have not somehow altered the formulation of the material to decrease costs and increase profits. The last batch I bought was a couple years ago...

 

[FINWIN]

Do you sun dry yours? Dry it out a lot? This is a bit disturbing to hear.

I love this product...and I really, really hope that they have not somehow altered the formulation of the material to decrease costs and increase profits. The last batch I bought was a couple years ago...

No I don't dry mine at all. Just rinse and re use. It held up just fine for a while. Then I noticed small crumbs breaking at the corners. Didn't think too much of it at the time but I have one block that is definitely tearing open in the middle almost like the cells are breaking down leaving hollow spots.

 

[Midwater]

Then I noticed small crumbs breaking at the corners. Didn't think too much of it at the time but I have one block that is definitely tearing open in the middle almost like the cells are breaking down leaving hollow spots.

Similar to what I am getting.

I am not going to sun dry mine anymore, but I am wondering about the various types and quality of foam available.

 

[FINWIN]

Similar to what I am getting.

I am not going to sun dry mine anymore, but I am wondering about the various types and quality of foam available.

Good point, I always assumed the brands were similar in quality.

 

[TwoTankAmin]

One of the main reasons I use Poret after the fact that is provides some of the best filtration I have found is it greatly reduce maintenance since it so rarely needs to be cleaned. I normally rinse cubefilters once a month rr even less frequently. Mattens go multiple years between cleanings. basically. it is only time toy clean them when the water level behind one is lower than the level in the tank.

I do multiple Mattenfilters and they need to be taken out and cleaned about every 4 or 5 years. I never let them dry out. In your filter I would have thrown out the pumice and used only Poret of varying ppi and no floss.

Poret, or equivalent quality foam, is about the best biomedia you can have. It will actually foster some amount of denitrification. The only better filtration would be a well planted, deep bed substrate.

In addition to sheets of Poret, I also have one 5x5x10 tower filters and then 1 cubefilters- a lotarf 4x4x4 and then a number of 5x5x5 and a three 3x3x3 as well. I have a total of 4 Mattens and then I have a bunch of Poret in my AquaClears. I also use 10 ppi Poret for pre-filters. Finally, I use 2 inch thick Poret sheets as tank dividers which means they are also filters. I use either 10 or 20 ppi for dividers.

Here is some of the relevant info on Poret on the Swiss Tropicals site:

Q: Why use Poret® foam and not any other reticulated foam?

A: Poret® was specifically designed for aquaria and pond filtration with these main properties: Chemically resistant to bacterial degradation and hydrolysis, high compression strength to prevent shrinking, hydrophilic surface facilitates colonization by beneficial microorganisms, controlled reticulation process gives it a much greater surface than other foams, completely non-toxic.

Q: How often do you clean/rinse a Hamburg Mattenfilters or Cornerfilters?

A: only when needed; as long as the water goes through, just leave it alone! The longer it runs, the better it works. Mattenfilter are mimicking soil biofiltration. There are Mattenfilters in continuous operation for over 10 years! This is a low maintenance filter media, and the larger the surface area, the longer it runs without clogging. In tanks with very heavy loads, and for smaller corner filters, you can rinse it more often if needed (quarterly, biannual, or so). However, be careful not to crash the tank by cleaning the filter sheet too thoroughly.

Q: What PPI of Poret® is best in a sump?

A: A basic sump needs no special design or expensive interior. The design is a bare tank equipped with a number of sheets spaced apart so that individual sheets can be removed for rinsing. The spacing makes it easy to spot when a sheet becomes clogged, because the water level in the gap before will increase. The design also permits the water to overflow to the next compartment without flooding the room. I recommend starting with a 10 or 20 PPI sheet to trap large particles first, then follow with 30 PPI as a polishing media last. Finer substrates tend to create a bottleneck, hence I do not recommend 45 PPI for sumps. The number of sheets and thickness depends on the tank and sump size, the tank inhabitants, feeding regime, i.e. the bioload.