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Thread: Flocculation - Pros and Cons

  1. #1
    Oyagoi yerrag's Avatar
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    Flocculation - Pros and Cons

    I occasionally use bentonite or zeolite to flocculate my pond. I only do it when the pond is not as clear as it could be, and only when I can attribute the turbidity to visible fines in the water column. Lately, I've been having second thoughts about the practice. And the reason for that is that while it clears up the pond water, I have strong suspicions that many of the flocculants go past my filter brushes, and end up on my biofilter Japanese matting. As a result, it hinders the operation of the biofilter and requires more frequent cleaning of the biofilter.

    So, now, I feel that a little turbidity is no big deal as long as I don't compromise the smooth operation of my biofilter.

    Instead, I should focus my attention on asking why I have turbidity, and it seems to me that this turbidity actually increases after I clean my biofilter. It must be that after the high pressure spraying with pond water of the Japanese matting, a lot of the loosened particles are not sufficiently drained away, and get dislodged back into the pond water column.

    I notice that my j-mats sag at the center, thereby blocking the bottom channel of the filter chamber, where the water should flow freely and unimpeded by the Japanese matting. But if the matting sags and blocks the bottom channel, it also keeps loosened particles (from spray cleaning) from being drained and thrown away. Once pond and filter comes back online, these particles get to flow into the pond to cause the turbidity.

    The next time I clean my biofilter, I'll put two 2-inch sanitary pipes along the length of the channel, in order to prop up the sagging mattings, so it will provide a clear path for water flow on the bottom channel of the chamber. I hope this can take care of the turbidity and allow me to dispense with the need for flocculants.

    Would appreciate very much your comments.

  2. #2
    Daihonmei MikeM's Avatar
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    I agree that it is best to identify the cause of the problem than to use additives constantly. I also agree that you want to avoid impairment of the biofilter function. Whether use of bentonite or zeolite interferes with nitrification in your pond, I cannot say.

    How serious an issue the turbidity may be depends on what is causing the turbidity. The usual culprits are algae pieces broken off of filamentous algae growing in the pond, greenwater algae and 'fines'. All of these are usually present to some degree. Bits of algae will get removed by any decent mechanical filtration. Greenwater algae will decline with adequate biofiltration (or use UV). So, the real question becomes what to do about those 'fines'. In some ponds, particularly those using un-filtered well water, the 'fines' may actually be clay/soil particles. In most ponds, however, the 'fines' are from fish waste and the food being fed. These 'fines' are troublesome because they are rotting in the water. Removing them is definitely a good thing to do. Complete 100% removal is not going to occur, except during periods when the fish are fasted. But, the more that 'fines' can be removed from the system the better. Many people use bead filters for this purpose. Old-style huge settlement chambers holding about a third of the volume of the pond do a good job, but few people have space for them. Vortex settlement chambers do not do so well because the the movement keeps the 'fines' suspended. Mats can work, but must be numerous, have very tight weave (which means it will get blocked sooner) and water flow must be slow. If you have carpet algae in your pond, you'll find that it holds fine debris that moves into the water column as koi graze and swim by.

    You may see more fines after cleaning the mats and brushes in your biofilter because when they are dirty the openings through which water flows are made smaller by the clogging. You can use a tighter weave mat (or thicker layers of mat) to get the same results, but you may need to clean the mats more frequently.

  3. #3
    Jumbo sacicu's Avatar
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    Quote Originally Posted by MikeM View Post
    I agree that it is best to identify the cause of the problem than to use additives constantly. I also agree that you want to avoid impairment of the biofilter function. Whether use of bentonite or zeolite interferes with nitrification in your pond, I cannot say.

    How serious an issue the turbidity may be depends on what is causing the turbidity. The usual culprits are algae pieces broken off of filamentous algae growing in the pond, greenwater algae and 'fines'. All of these are usually present to some degree. Bits of algae will get removed by any decent mechanical filtration. Greenwater algae will decline with adequate biofiltration (or use UV). So, the real question becomes what to do about those 'fines'. In some ponds, particularly those using un-filtered well water, the 'fines' may actually be clay/soil particles. In most ponds, however, the 'fines' are from fish waste and the food being fed. These 'fines' are troublesome because they are rotting in the water. Removing them is definitely a good thing to do. Complete 100% removal is not going to occur, except during periods when the fish are fasted. But, the more that 'fines' can be removed from the system the better. Many people use bead filters for this purpose. Old-style huge settlement chambers holding about a third of the volume of the pond do a good job, but few people have space for them. Vortex settlement chambers do not do so well because the the movement keeps the 'fines' suspended. Mats can work, but must be numerous, have very tight weave (which means it will get blocked sooner) and water flow must be slow. If you have carpet algae in your pond, you'll find that it holds fine debris that moves into the water column as koi graze and swim by.

    You may see more fines after cleaning the mats and brushes in your biofilter because when they are dirty the openings through which water flows are made smaller by the clogging. You can use a tighter weave mat (or thicker layers of mat) to get the same results, but you may need to clean the mats more frequently.
    Seems to me Mike that Eric type filtration does not conform to the explanations you made and yet so many ponds worldwide are able to achieve quite good clarity as well.

  4. #4
    Daihonmei MikeM's Avatar
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    Quote Originally Posted by sacicu View Post
    Seems to me Mike that Eric type filtration does not conform to the explanations you made and yet so many ponds worldwide are able to achieve quite good clarity as well.
    Is it inconsistent? I wouldn't think so. But, my only familiarity with the ERIC filters is what I've seen posted on the internet. I have not seen an ERIC in operation. I would put ERIC filters in the multi-chamber filter class, which is the sort of filter that was most utilized in the hobby before pressure filters and moving kaldnes filters came along. The multi-chamber type filter always did a very good job of mechanical filtration if the design involved a lot of mats and required the water to flow through the mats. Prior to my current pond, I primarily relied on a multi-chamber type filter from Pondwise. (I don't know if they are still in business. Their fibreglass filters were fairly expensive due to shipping costs. The Litek filters out of Taiwan are similar, not nearly as expensive, but not as well-designed nor as sturdy.) I got very good mechanical filtration. The challenge was the blockage of the mats by all the gunk they captured.

    On the ERIC website their mats are promoted as being special because they have a tighter weave:

    "These are responsible for much of the remarkable performance of all Eric Filter units. This grey material is 30% denser than the best quality blue/green filter mat and is unique to Eric Filter Systems. This is supplied from the manufacturer (ENKEV) in 500mm x 380mm x 19mm sheets specifically to form the EricMat Blocks. These blocks are built with two polypropylene sides and held together with four stainless steel bars secured by nylon-threaded screws at both ends. In all, seventeen sheets of 19mm thick EricMat are used to make up one block. Size for size one of these blocks produces three times the surface area of a cartridge formed from traditional blue/green filter mat sheets."

    The larger ERIC models have 24 of these mat assemblies and recommend a flow rate not exceeding the pond volume over two hours. So, I'd think they would do well in mechanically filtering the pond, as my old Pondwise filter did.

    The issue with mats is always keeping them clean enough that the bio-filtration function is not impaired. With the ERIC, the brushes are supposed to capture enough gunk in the first stage to avoid having to clean mats so frequently that it becomes too much work. My old Pondwise filter used brushes in the first stage also, but as good a job as they did, gunk still got through to block the matting. The mats had to be cleaned every few weeks and really should have been cleaned weekly. (This just required sloshing them around in pond water, but it took almost an hour. That was too much time lost every week to suit me.) Settlement chambers first became popular because they helped lengthen the time between cleanings of the mats. But, they took up so much space, the vortex settlement chamber became popular because it was more compact. The vortex settlement chamber did a great job in a small space, but at the cost of allowing fines and neutrally buoyant debris to move to the mat stage.

    I know there has been controversy over Waddy's marketing claims about ERIC filters, but there really cannot be much controversy over the concept. It's a tried and true method of accomplishing good water as long as properly maintained. I would expect it to keep fines low, at the cost of more time spent cleaning mats.

  5. #5
    Nisai
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    Mike , Wont it be better if you could get a Polishing System for the water .... ie one more layer of mechanical filtration just before water is released back into the pond .. Poly wool does a great Job here , as you can just throw it way -- or reuse it later after washing ans sun-drying ..

    if you use the output polisher for a day or so on the filter cleaning day .... you should be able to remove any suspended solids that would hinder clarity ...

  6. #6
    Daihonmei MikeM's Avatar
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    Some filter systems may not need a final polishing stage because the amount of bio-media serves the purpose. Of course, it depends on just how free of fines a person wants to be. A final polishing stage is often needed if the hobbyist really wants truly clear water without even a haze when the sun shines at an angle. There are several techniques used as a 'final polish' step to remove fines. All of the ones I've seen that are truly effective get clogged quickly, which is going to happen if a technique is effective. So, the issue becomes the hobbyist's willingness to clean regularly, which translates into: How easy is the cleaning chore? How much time does it take? How frequently must it be done? Something may be quick and easy, but if it must be done daily (or more than once per day!!) people will end up frustrated by it.

    I've not seen poly-wool used on a pond. I have seen it used on aquaria. It captures an amazing amount of stuff even where the water seems clear and clean. So, it gets clogged in short order. It is comparatively cheap. Cleaning is a messy chore. I can see it working acceptably on a small pond if things are set up such that cleaning does not have to be more frequent than once per week. (On my aquaria, I use two sponges as the first mechanical stage, followed by poly-wool and lastly a 'filter cloth' (50-micron felt) prior to bio-media.)

    Bead filters do well, but can still leave a haze in the water from micro-particles of waste unless the water is very well filtered first. (Going through the pump prior to the bead filter really pulverizes even the tiniest debris.) Sand filters do a great job if placed as the final stage for fully filtered water, and the unit is designed to have effective backwashing (and the unit is large enough that cleaning does not have to be too frequent). One approach I saw on the internet, not in person, was in Germany (I think) where an enormous settlement vat was placed at the end of the filtration system, with a water flow so slow even micro particles settled out. I assume it worked as well as was said, I did not see it in person.

  7. #7
    Oyagoi yerrag's Avatar
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    KK, your idea of an output polisher on cleaning day and a day after sounds good. I have to find out what polywool is although I have annidea of what it is.

    Mike, thank you for giving a very enlightening rundown of the challenge of managing fines on a traditional brush filter and map mat system. I have the traditional blue/green mats, and I agree that fines can get through them and that a bit of turbidity in the pond is the result. My answer had been to use flocculants and they really clear up the pond. The danger is that by clearing up the pond with flocculants I am plugging up my Japanese mats more quickly. So the only time I can really use the flocculant is a day before I clean my filter- sump, brush filter, and map mats. I get to rid the pond of fines, and then rid my biofilter of flocculant remnants on filter cleaning day. And to keep dislodged fines from the cleaning of matting from getting to the pond, I adopt KK's method of polywool polishing.

    Of course fines will slowly accumulate in the pond's water column in between filter cleaning, but at least the use of flocculant right before filter cleaning plus polywool polishing will keep fines from accumulating over time.

  8. #8
    Nisai
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    Quote Originally Posted by yerrag View Post
    KK, your idea of an output polisher on cleaning day and a day after sounds good. I have to find out what polywool is although I have annidea of what it is.

    Mike, thank you for giving a very enlightening rundown of the challenge of managing fines on a traditional brush filter and map mat system. I have the traditional blue/green mats, and I agree that fines can get through them and that a bit of turbidity in the pond is the result. My answer had been to use flocculants and they really clear up the pond. The danger is that by clearing up the pond with flocculants I am plugging up my Japanese mats more quickly. So the only time I can really use the flocculant is a day before I clean my filter- sump, brush filter, and map mats. I get to rid the pond of fines, and then rid my biofilter of flocculant remnants on filter cleaning day. And to keep dislodged fines from the cleaning of matting from getting to the pond, I adopt KK's method of polywool polishing.

    Of course fines will slowly accumulate in the pond's water column in between filter cleaning, but at least the use of flocculant right before filter cleaning plus polywool polishing will keep fines from accumulating over time.
    Well Yerrag , Polywool is short for Polyester Wool (same stuff what is used in filter pad ) Best and economical source is just buying new pillow and take the batting out ....should cost you around 1$ USD and the stuff is reusable you just need to pressure wash it (you don't need very high pressure too)...

  9. #9
    Nisai
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    Quote Originally Posted by MikeM View Post
    Some filter systems may not need a final polishing stage because the amount of bio-media serves the purpose. Of course, it depends on just how free of fines a person wants to be. A final polishing stage is often needed if the hobbyist really wants truly clear water without even a haze when the sun shines at an angle. There are several techniques used as a 'final polish' step to remove fines. All of the ones I've seen that are truly effective get clogged quickly, which is going to happen if a technique is effective. So, the issue becomes the hobbyist's willingness to clean regularly, which translates into: How easy is the cleaning chore? How much time does it take? How frequently must it be done? Something may be quick and easy, but if it must be done daily (or more than once per day!!) people will end up frustrated by it.

    I've not seen poly-wool used on a pond. I have seen it used on aquaria. It captures an amazing amount of stuff even where the water seems clear and clean. So, it gets clogged in short order. It is comparatively cheap. Cleaning is a messy chore. I can see it working acceptably on a small pond if things are set up such that cleaning does not have to be more frequent than once per week. (On my aquaria, I use two sponges as the first mechanical stage, followed by poly-wool and lastly a 'filter cloth' (50-micron felt) prior to bio-media.)

    Bead filters do well, but can still leave a haze in the water from micro-particles of waste unless the water is very well filtered first. (Going through the pump prior to the bead filter really pulverizes even the tiniest debris.) Sand filters do a great job if placed as the final stage for fully filtered water, and the unit is designed to have effective backwashing (and the unit is large enough that cleaning does not have to be too frequent). One approach I saw on the internet, not in person, was in Germany (I think) where an enormous settlement vat was placed at the end of the filtration system, with a water flow so slow even micro particles settled out. I assume it worked as well as was said, I did not see it in person.
    You are correct as always Mike .... gravity and vortex Settlement vats are used lot ... so are final fine removers (sieves or sand ) .. especially in Aquaponicssystems (between output of filters and input to the growbeds )as their Pipes would clog and the grow media would channelize because of the fines ... Channelizing for them means wet and dry areas in the grow-bed and so crop loss ...

    Now my suggestion was not in the way used in aquaria ...but only at the output and only on the cleaning day (the only day your filters are not performing to the optimum) ... so any waste that the cleaning stirs up will be caught in the battering .. and believe me a large wad , when its fresh ie. say a day old is cleanable in 10 minutes if you put it on the ground & just hose it down ....if you have too much fines you can use two large wads and alternate between then ,so that by the time you have finished cleaning the filter all you fines are also out of the system ...

    now why i don't actually support flocculation is because it need not necessary mean that the fines are out of the system but they are allowed to travel freely and resettle in the filter mats , so the problem is remedied temporary and not actually eliminated..

    .If you try it a last stage polish on your output I am sure you find it quick ....U don't need any new equipment but just figure out a way to hold the batting under your pond inlet ... Much easier than a settlement Vat or sand ...

    Now all this is under the assumption that the turbidity is due to the cleaning fines only ....

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