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Thread: pea gravel or lava rocks?

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    toofazt is offline
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    pea gravel or lava rocks?

    I'm going to be making a bog filter for a pond. Everything I've read says to use larger rocks for the first layer and then 3/8'' pea gravel. I would think the crushed lava rock would be better because of more surface area for biological filtration. The only draw back I could see is the lava rock getting clogged with dibree. I don't think that would happen though, would it?? Also for the larger first layer of rocks is there a certain type of rock that works best (like not changing the chemistry of the water)?

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    Probably not going to find a lot of support for gravel filters here, partly because they are so difficult to clean (being full of really heavy stuff and all) and partly because portions can plug, become anaerobic, and potentially cause problems. I'm using one, it holds about 18 tons of river rock. The first foot is large rock, 3" to 6" size hand laid. The balance (3') is 1" river rock, less surface area but very difficult to plug. I'd avoid lava rock - as you comment, it will plug with debris and soon offer no advantage over smooth rock. Also, be careful to design it so you can drain it periodically to flush debris. Not a slow drain, large pipe fast drain would be more effective me thinks. Mine's a compromise with 3" pipe, but it's got 4' head so it drains pretty fast when I ask it to. A grid of air lines between the water lines allows you to air bump the bed and dislodge potential debris, I set mine up to run continuously off a 50 LPM pump, can hook up a compressed air source for a more powerful blast. If your filter is large, as it has to be for efficacy, it will be a major pain to remove and clean the bed. Perhaps a real expert will jump in and offer advice.

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    toofazt is offline
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    So is there another biological filter that is DIY and inexpensive? Thanks for your help

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    Quote Originally Posted by toofazt
    So is there another biological filter that is DIY and inexpensive? Thanks for your help
    You have no idea. There are tons of them out there. You just have to search this forum and find the right one for you. There are skippy filters, trickle towers, moving bed, upflow, downflow, microscreens, gravel, and plenty of other types of filters.
    Just find the right one for you. Many people use different types of filter media also. Floor scrubber pads, K1, bioflow, strapping , PVC shavings, almost everything has been used before.
    Just search the forum. There are some very good ideas. There is also a thread that has every DIY item ever posted, I think, on one thread.
    Steve


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    CarolinaGirl is offline
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    Check out this thread: http://www.koiphen.com/forums/showthread.php?t=38259 there are links to tons of great DIY filter projects. Lava rock and pea gravel are WAY too hard to clean. Filters that are not kept clean harbor bacteria and parasites. A clean filter creates a much healthier environment for your fish.

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    --rock media.
    just plain heavy to clean. and when ya upside down. trying to get the last few inches out of a filter. ya learn rather quickly.

    ---foams, mats, brushs.
    japneese matting, matala, kitchen scrubies, floor pads, verying types of foams, and mats, bottle brushs (black knight brushs seem to be better of brushes for pond filers). most are time consuming cleaning and some times splattering debree smelly fun. normally, requires physical removal of the media out of the filter. then a garden hose to clean.

    ---plastic media
    k1, bio barrels, bio balls, beads, new plastic shot gun wads. or other small size plastic peices. there normally small enough. that you can either use an air pump. or some other form of compressed air. to send through the plastic media. to get the media fairly well cleaned. without much hassle.

    or in case of a moving bed / fluidized bed. there really is not a hole lot of cleaning to do at all. due to the media would most likely be self cleaning.

    ---misc media.
    scraping, pvc shavings, strings, ropes, even lego's could work, though lego's might be abit of a pain to clean.

    ---personally. rocks might be cheap. but a pain in the rear to clean. id prolly never use rocks if all possible again. or less decoration / landscaping. i might consider foam/mats/brushes. if a situation or i found some nice little deal for a great price for some. personally would if possible save up for a plastic media.

    --------------

    ---some things to think about in a filter to help cleaning.
    ------can compressed air from an air pump, lawn blower, air compressor, or what not, be used, to pump air into the bottom of the filter. and be used as a way to help clean the media?
    ------if media is small, can the media be put into, media bags, nylon bags, netting or something. to help make it easier during cleaning?
    ------different types of media, and filter setups can work better for mechanical filteation vs bio filteration.

    ----------------

    ---trickle towers / bakki showers
    its the one type of filter. that rocks seem the best with. due to nearly most of the time. the rocks are put in crates. were the crates themselves. are easy to remove from the main filter and to wash off when need be.

    ---kent's EZR filter (sand and gravel filter) could be a descent filter over just a plain rock filter.

    ---bog filters. aka ((using watergarden pond as a filter))
    not many really like the idea of using a bog filter. as a filter. due to the con's out weight in most situations the pro's of such a filter. more so how the bog filter can impact the rest of the pond.

    some folks may go as far as stating. to split up a pond with fish and plants. and create 2 seperate ponds. one for plants one for fish. and choice being for, maintence, water chemistery, treatments, cleanings, to etc.
    Pond and Construction Forum 101 good place for any first timers to the forum. for finding resources and general info.

    Ryan

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