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gravel v. ceramic tubes
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Angry Andy
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Joined: 26 Sep 2006
Location: St. John's, NL, Canada

PostPosted: 2007.01.03(Wed)18:10    Post subject: gravel v. ceramic tubes Reply with quote

Does anyone here use bagged gravel as opposed to ceramic tubes in their filter media, and if so- how does it compare?
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richiestang_78
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Joined: 13 Oct 2003

PostPosted: 2007.01.03(Wed)21:53    Post subject: Reply with quote

Never seen gravel used as a bio filter media, he ceramic are made to have a very high surface area so I would just go with them. Where did you see this gravel?
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Angry Andy
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Joined: 26 Sep 2006
Location: St. John's, NL, Canada

PostPosted: 2007.01.03(Wed)22:13    Post subject: Reply with quote

I've never seen gravel used in this manner, but it had occured to me just how practical this alternative could be.

Two issues I see of concern using gravel as bio-filter media:

- impeding return water flow (how much is 'too much' in the filter?)
- compromising the amount of nitrifying bacteria due to an inadequate amount of porous surfaces (what kinds of crushed rock/aquarium gravel are most suitable for this application?)
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richiestang_78
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PostPosted: 2007.01.04(Thu)2:21    Post subject: Reply with quote

I don't think the gravel would really slow the water flow down that much, I would be more concerned with he lack of surface area. Aside from sand I don't see gravel having any benefits over ceramic, just stick with that.
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Bob
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Joined: 16 Jun 2006
Location: UK

PostPosted: 2007.01.04(Thu)4:51    Post subject: Reply with quote

Yes it's all down to surface area, we are looking to encourage millions of bacteria to take up residence in our filters, they only live on the surface of something, where Oxygen rich water can pass them.

If you look at a ceramic particle you would probably see a very pitted surface, that could hold many times the amount of bacteria compared to a piece of gravel with it's polished surface.

A long time ago when I first started keeping Koi, I used to make my own filters (There was no commercial units available for what I was doing). I used to use 50 gallon coldwater storage tanks, sometimes linked in series (Yes I have had a 150 gallon filters before), for media, I came up with the idea of using Coke (Coal with the gas driven out), the massive surface area ment I could filter really very large ponds with these filters. If I had used gravel the sizes would have needed to be twice or three times larger.

Again because of the size of the filters, and the design of the ponds (I designed them so the so cr*p fell away from the filters inlets, and was syphoned off seperatly, so not much cleaning of the filters was needed.

Foam and sponges are good filter media for the same reason, and are an awful lot easier to clean than wheelbarrow loads of Coke, so I changed media when foam sponges became more readily available.

If you think about a UG filter, it uses gravel, but it does this over a very large (Shallow) area, so although gravel isn't as good as modern media, the UG makes up for this by increased volume, something you wouldn't want to do in a normal filter. I am not knocking UG filters, I think they still have a place in certian areas of fishkeeping, but a modern cannister filter, is far more efficient with modern media.

Hope that helps.

Bob
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unissuh
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Joined: 29 Mar 2005
Location: Melbourne, Australia

PostPosted: 2007.01.04(Thu)5:51    Post subject: Reply with quote

Just to add a comment that nobody has picked up on yet: if you let water drip down through the gravel, you will find that most of it gets clogged very quickly and water will mainly flow down through 'channels' in the gravel...much of the surface area becomes useless very quickly. This problem is common in calcium reactors in marine tanks...the solution? Pump water UP through the gravel, not drip it down.
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Angry Andy
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Joined: 26 Sep 2006
Location: St. John's, NL, Canada

PostPosted: 2007.01.04(Thu)13:47    Post subject: Reply with quote

Thanks, everyone.

From the beginning, this wasn't a serious consideration- just a hypothetical scenario I was proposing. I figured that the surface area would be the biggest issue of concern.


On a related note, how often do you (not 'should you') rinse/replace ceramics?

Fluval's specifications state to rinse the ceramics monthly and to replace them every 6 months. I don't see the point of doing either.
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Bob
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Joined: 16 Jun 2006
Location: UK

PostPosted: 2007.01.04(Thu)16:00    Post subject: Reply with quote

I assume this is in an external cannister filter, the answer would be very different if this was in a small internal filter.

Depending on stock load, type of fish etc, external filters can go months between cleaning at all, and then it's normally a quick rinse of the foam elements. Whilst I was doing this I would also give any other media a rinse in old tank water as well.

As to replacing any filter media, I would only do so when the stuff was actually falling apart, or had become so blocked up that it had lost it's usefulness.

Filter companies are naturally out to make money, you can't blame them for trying Wink

This is very different for Active Carbon, this only remains useful for a short time (Weeks), so it either needs replacing at least monthly, or better still take it out, and replace it with other media, and only use it when needed (Taking out medications, or known pollutants).

Bob
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unissuh
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Joined: 29 Mar 2005
Location: Melbourne, Australia

PostPosted: 2007.01.04(Thu)22:04    Post subject: Reply with quote

I never touch the ceramic noodles except to access the sponge/filter wool underneath in my AC30. I've used those particular noodles for about 2 years now and have never rinsed them. I don't notice much gunk building up on it, definitely not enough to impede flow through...most of it is removed by filter wool and the sponge located previous to the noodles.
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