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I wish Oase

Joined
17 Mar 2012
Messages
2,003
Location
Dorset
Would sell Carbon filter foams for the trays. It would save me the bother of cutting them out.

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I’ve no idea as I’ve not used them before. I have been using carbon granules and that works but not so easy to implement well due to the shape of the filter baskets.
 
The top basket is the same shape so with anything that is in bags you get plenty of bypass.

I don’t use carbon, but my bagged up purigen still gets nice and brown over a period of time, so whilst it’s not 100% efficient, I’m guessing it’s still doing it’s job.
 
The amount of 'carbon' in the foam shown in the photo above would be miniscule compared to a bag of activated carbon?
Does the manufacturer of such foams even bother to state how much activated carbon is added to the foam? I guess if the manufacturer had a non-carbon foam of similar ppi, you could weigh both to them to see if there is any weight difference. It would certainly be much less than say, a small 100g bag of activated carbon

My Fluval filters came with a few bags of activated carbon. I tried them out but could not ascertain whether they made any difference in my tank. However, I am using a small bag of purigen which refreshes in bleach pretty efficiently
 
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As a carbon sponge. I wouldn’t be expecting it to be great for bacteria, I would want it to do the job of regular carbon and clean the water, unless I’m missing something here?

The problem as mentioned seems to be how much carbon is needed.... A 100g bag of activated carbon lasts between 2-4 weeks

if the sponge pictured above has 10g of activated carbon added to it (and that might be a generous estimate- only weighing it and comparing with a non-carbon sponge will give a more accurate estimate), the carbon will probably last 1-2 days? Not sure how much 'cleaning' that amount of carbon will do.
 
When I ran a Tetra EX600 on the tank with a bag of Carbon in the top tray it did a good job of removing tannins from the tank. The EX600 has roughly square trays though so it wasn’t too difficult to spread a mesh bag with carbon in it over the entire tray to minimise bypass. This is not possible due to the shape of the trays in the Biomaster though. This is perhaps why Oase sell Carbon Foam filters for the Prefilter. The carbon foam is noticeably heavier than plain foam but how long it will last I don’t know yet. A bag of carbon seemed to last up to maybe four weeks before the tannins were noticeable again.
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The problem as mentioned seems to be how much carbon is needed.... A 100g bag of activated carbon lasts between 2-4 weeks

if the sponge pictured above has 10g of activated carbon added to it (and that might be a generous estimate- only weighing it and comparing with a non-carbon sponge will give a more accurate estimate), the carbon will probably last 1-2 days? Not sure how much 'cleaning' that amount of carbon will do.
Hence why I originally asked if they’re any good.
From what you’re saying. Clearly they’re not.
I actually have no interest in carbon sponges. I think they’re pointless, but thought I’d ask, as I have no experience with them and would be happy to be given a different opinion to the one I already hold.
Not really sure what you’re implying either with your ‘cleaning’, are you implying that’s not what carbon does to the water in effect?
 
When I ran a Tetra EX600 on the tank with a bag of Carbon in the top tray it did a good job of removing tannins from the tank. The EX600 has roughly square trays though so it wasn’t too difficult to spread a mesh bag with carbon in it over the entire tray to minimise bypass. This is not possible due to the shape of the trays in the Biomaster though. This is perhaps why Oase sell Carbon Foam filters for the Prefilter. The carbon foam is noticeably heavier than plain foam but how long it will last I don’t know yet. A bag of carbon seemed to last up to maybe four weeks before the tannins were noticeable again.View attachment 195551
I think carbon is still effective, even if it’s not spread across the surface of the tray, provided it’s in a good area for water flow and not before your media it should work perfectly fine?
 
Any manufacturers suggestion will be a mix of marketing and guesswork. You will always need to eye ball it because it will depend on how much it absorbs, how quickly. Other manufacturers used to suggest 6 weeks for a sponge but that's a little optomistic in a high tannin environment.

Personally I don't think it matters where carbon is in the system, wholesalers used to just dump a bag in the sump to remove meds and there wasn't the greatest turnover. Carbon works like a sponge and ideally, slower turnover, is perhaps better.
 
If tannin removal is the goal then I guess a ‘suck it and see’ approach may be best as you will get visual feedback pretty quickly.

You may find that a bag of carbon that doesn’t cover the entire tray still does a better job, for longer, than the sponges….or not!

As for bacteria, I agree that sponges are good for this and use them myself, but if you are throwing them away every few weeks, it’s probably not as efficient for your overall eco system as they would be effectively starting again when replaced…...but I don’t think this is the goal anyhow right!
 
I did try a bag of carbon in the Biomaster but it didn’t get rid of the tannins for very long. Once the mesh bag gets a little bit clogged I suspect the flow just goes round it rather than through it.
As a point of interest I’ve just weighed a 50mm thick Oase Blue foam at 28g, so 14g for 25mm. The carbon foam seems to be a similar porosity but weighs 43g but is only 25mm thick. This means there’s probably around 29g of carbon in it, more than I expected.
I’ll try it out in a week or two and see how it works. I got 4 filters out of an 18”x12” sheet of foam at £15.49 so £3.87 each. I kept the offcuts as I can use the pieces in the tray on their own so I suppose it works out at maybe £3.00 a fill.
 
I’ve installed one of the carbon foams and it’s maybe made a slight difference but not much. 🙁 Back to using carbon granules again I suppose?
 
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