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Tarutan 05-21-2013 07:14 AM

Questions about carbon
I have a fluval c2 filter for my 10 gallon tank, in it are 2 platties a dwarf frog and I plan to complete it with a dwarf gourami. The fluval c2 has three filter compartments. A sponge, chemical, and bio. Alot of people are telling me to just never change the sponge so my tank will have alot of bacteria. They also say carbon isn't necessary and to use a bio media in that chamber as well. Do I really need all that bio media?

how is it not necessary? If carbon removes dissolved organics it cleans the water doesn't it? Ideally I would like to swap the sponge and carbon regularly to keep the water quality clean especially in a closed off environment that has no other exit for impurities.

So wouldn't all the surfaces in the tank(tank walls, sand surface, castle, plants, driftwood, dedicated bio chamber in the filter, filter walls) hold enough bacteria to take care of 2 platties, a frog and a dwarf gourami? I am speaking in terms of a cycled tank, as for now I am not replacing any media until that completes.

jaysee 05-21-2013 07:26 AM

There is no need to change the sponge, but you would certainly need to clean it periodically. I know it may be counter intuitive, but a "dirty" filter makes for clean water. You don't want to mess with the filter too much.

Whether to use carbon or not is your own choice. Many people, myself included, have stopped using it years ago, and we put additional mechanical or biological media in the filter. In my opinion you cannot have too much biomedia.

Use carbon if you want, don't use it if you don't - makes no difference in a well balanced tank. Many people that have planted tanks don't use carbon because it adsorbs things the plants use. Some people have smelly water and use carbon to cover it up - NOT a good idea. If your water smells, there's something wrong and covering it up is not the answer. Some people swear it makes their water clearer, and others (myself included) could tell any difference once they stopped using it. It's one of those things that you have to figure out for yourself.

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Geomancer 05-21-2013 07:28 AM

First the sponge, it is true you never need to replace it. That does not mean you do not need to clean it. At every water change, you should at least squeeze it out and swish it around to get all the gunk out. Aside from that though, you can keep using it until it literally falls apart.

The only purpose of a sponge, or other filter pads, is just to block solid particles so the water looks clear. So it isn't really filtering anything out of the water (all the waste is still there) it's just keeping it out of the water column and making it easy to remove at cleaning time.

Now for carbon. The short answer is, no this is not needed. With no live plants it may serve a small use, but the issue really is that carbon gets used up very fast. Faster than once a month. So it becomes expensive, and offers little to no benefit if not frequently replaced. Putting live plants in the tank offers a much better improvement than carbon ever could give.

Bio media. This is more important in the first months than any other time. You are correct that the substrate and all the other surfaces will eventually have far more bacteria than the filter, making its contribution to bio filtration less and less significant as a percentage. So do you need more? No, it won't give you any benefits other than letting you stagger cleaning them, which means you could do a deep clean in the chlorinated tap water on one, while leaving the other in the tank. You could also use the second to seed a future tank, if needed.

Again though, live plants are better biofilters than the bacteria. So if you can't tell, I'm a big fan of live plants ;)

AbbeysDad 05-21-2013 08:10 AM

I think mechanical filtration works best if the filter (sponge or pad) is cleaned often to remove the crud from the system. I rotate sponges/pads, then clean for reuse. Bio-filtration works best if/when the media is undisturbed and the flow rates are slow. Hard to do both in conventional filters.
The very action of a filter rapidly reduces any solid waste to dissolved organic compounds that pollute the water.

I tend to agree that bio-filtration (way beyond N2 oxidation) can be enhanced with more media and slower flows.

As for activated carbon, it's been used for decades not only in aquariums, but to filter/purify drinking water. Every aquarium filter marketed today is designed to use it and most include some. This alone tells us something.
Carbon adsorbs all sorts of impurities. It is true that carbon will remove some of the impurities that plants would use as nutrients.
I think the biggest negative with activated carbon is that the amount typically used in aquarium filters is not enough to make a difference for any length of time. But increase the amount and I think some would be surprised at the performance.

So if you'll have a planted tank (or floating plants) you might want to skip using carbon, or only use it occasionally. Otherwise, it's good to use it.
Here's an interesting read written by Dr. Tim Hovanec:
Activated Carbon | DrTim's Aquatics

In the end, every hobbyist has to decide.

Tarutan 05-21-2013 05:01 PM

Thanks for that link, it was informative. I decided I will continue to use carbon. It is only a small amount so I bet it won't starve my plants, but instead balance with them in filtering the water. That is my feeling. We will see!

I still have questions about the sponge however. The fluval C2 has an indicator for when the water isn't passing through the sponge. My indicator has only slightly risen, and swishing the sponge around in water to remove gunk didn't bring the indicator back down. The sponge is a pad actually, it is a 2 layer pad. First layer with larger pores to catch large gunk, and the 2nd part of the pad is finer. I tried squeezing it out, I brushed off all the large gunk from the outer pad but it didn't help with flow. The 1st layer remains clean but the 2nd finder layer has gotta dark all over.

The pad has only been in there for 20 days. What do I do when it is blocking flow since swishing it around isnt helping?

Tarutan 05-21-2013 05:09 PM

My plants are flourishing by the way. If you click on the link in my original post, it will take you to a picture of my tank. The anubias on the left was as small as the anubias on the right when I got it. Now it is huge after only a month and a half. The wisterias are growing fast, the cryptocyrnes are growing. I have been using carbon since the beginning.

jaysee 05-21-2013 05:10 PM


Originally Posted by Tarutan (Post 2112785)
The pad has only been in there for 20 days. What do I do when it is blocking flow since swishing it around isnt helping?

I thoroughly rinse my mechanical media with tap water - I have plenty of biomedia in my filters, and the bacteria will recolonize the sponge. A thorough cleaning does not sanitize the sponge. Any time you mess with the filter, it's a good idea to skip a day or two feeding, to allow things to balance back out. The last thing you need to be doing when the bacteria colony has been compromised is adding to the bioload.

Maxillius 05-23-2013 08:59 AM

Hi! I have a 26 G with a fluval c3 and I have been using the same sponge for a year and a half!
really you should only worry about the flow when the wet/dry trickle basket dosent have enough flow or when the water starts to flow out of the box back intoo the aquarium by another place then the intended.
as for the carbon with live plants its a no no even tho they are flourishing they could flourish more with out the carbon! I use purigen here Seachem. Purigen
It gives unparalleled water clarity and you can reuse it none stop!
Seachem. The Bag
is actually a bag of purigen that fits perfectly intoo the fluval c3 so maybe 2 for the c4?
anyhow if you have carbon and plants its like haveing 2 things that does the same thing, cleaning the water, but one you just keep buying for nothing :)
your plants will absorb what the carbon is absorbing. I just like to add purigen to my tanks because since I use it my water is really cristal clear! and it fills the hole in my filter with something usefull!

Byron 05-24-2013 02:52 PM

Using Purigen is much the same as carbon when it comes to live plants. Either/both do remove nutrients that plants need, especially DOC (dissolved organic carbon) in the case of carbon, which is often in short supply in the first place, and in the case of Purigen it removes nitrogenous organic waste (as Seachem state it) and this is essential for plants that need ammonium. The effect of Purigen on "trace elements" is said by Seachem to be minimal, but even this bothers me; plants need these too.

I freely admit that plants may still manage with carbon or Purigen. But I myself won't waste money on these products when live plants will do all this permanently, and the products do have some detrimental effect. I won't argue that Purigen might make the water a bit clearer than without, but I know I wouldn't see this difference in my tanks.


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