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Thread: Shutting Down the Bottom Drain and Just Relying on Skimmer

  1. #1
    Oyagoi yerrag's Avatar
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    Shutting Down the Bottom Drain and Just Relying on Skimmer

    I've been wanting to improve my filter's capability, particularly in the reduction of fines accumulating on my jap mats and/or going back to the pond and increasing the turbidity as a result. It points to my sump having a low retention time and not helping also is my sump not having a vortex design. As a result, my brush filter traps plenty of what should have settled, and what's trapped in time turns to fines and gets thru to my bio-filter chambers. What the bio-filter jap mats don't trap gets thrown back into the pond, increasing the turbidity. A solution would be more frequent cleaning of the filter, and the use of flocculants, but these solutions are problems in themselves, as they involve more work. When simplicity is substituted by tediousness, something has to be done, or nature's grim sentence takes over and makes the decision for me.

    As we all know, major redesign is a bear, especially difficult when you have a fully stocked pond of koi you don't want to risk putting in harm's way. So simple tweaks is the order of the day. And so I present to you my tweak and would appreciate your comments and suggestions.

    My 20-ton pond has one 4-inch bottom drain and two 3-inch surface skimmers that connect to the sump. Pond flowrate is 10k lph. This flowrate can be maintained when the 2 skimmers are plugged up and the bottom drain left on its own. Likewise when the BD is plugged up and the skimmers left on their own. Knowing this, I've decided to plug my BD. This allows the filter to take in water from the pond's surface, which is generally cleaner, except for floating solid fish waste and leaves. These are easily filtered off by a coarse plastic screen. As a result, I have much cleaner pond water, as far as solids and fines are concerned, going into my bio-filters, where as usual, the regular nitrification cycle takes place. Less fines accumulating on the jap mats makes for less need for cleaning. The return water to the pond is less turbid as well.

    In shutting down the BD, I am letting solid wastes settle onto the center-sloped pond bottom. The plan is to do a daily flush of the pond bottom, thru the bottom drain.. Success is based on how well the flush cleans the pond of its solid wastes. The more solid waste settles on the pond center bottom, the more waste gets flushed. To aid in this, I plan to move my Matala diffuser from the bottom side to the center bottom so that it is above the BD cover. This should help draw wastes toward the center, a function previously being accomplished with the now-decommissioned bottom drain. If circulation is still found to be lacking by the presence of solid wastes around the pond, I will have to restore the TPR (tangential pond return).

    I have redirected return water from the filter fully to my waterfalls, thereby plugging the TPR, in order to increase oxygenation. This was brought about by my concern that plugging the BD might compromise top-bottom circulation of the pond, causing the bottom strata to be robbed of adequate dissolved oxygen (DO). I don't know if this concern is justified, as there is a Matala diffuser vigorously providing aeration which continually brings to the surface water from the bottom. By the way, pond height is 5 ft. at center sloping up to 4 ft. at the sides.

    I will be looking for signs of dead spots, circulation-wise, so I can make some more modifications to address this.

    In all this, I would have kept fish waste from needlessly compromising my biofilter's cleanliness and effectiveness, and from making my pond turbid. If needed, I will also use flocculants to aid settlement of fish waste.

    I would appreciate if you could voice your concerns as I am sure I'd have overlooked a few areas. Thanks.

  2. #2
    Jumbo sacicu's Avatar
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    Quote Originally Posted by yerrag View Post
    I've been wanting to improve my filter's capability, particularly in the reduction of fines accumulating on my jap mats and/or going back to the pond and increasing the turbidity as a result. It points to my sump having a low retention time and not helping also is my sump not having a vortex design. As a result, my brush filter traps plenty of what should have settled, and what's trapped in time turns to fines and gets thru to my bio-filter chambers. What the bio-filter jap mats don't trap gets thrown back into the pond, increasing the turbidity. A solution would be more frequent cleaning of the filter, and the use of flocculants, but these solutions are problems in themselves, as they involve more work. When simplicity is substituted by tediousness, something has to be done, or nature's grim sentence takes over and makes the decision for me.As we all know, major redesign is a bear, especially difficult when you have a fully stocked pond of koi you don't want to risk putting in harm's way. So simple tweaks is the order of the day. And so I present to you my tweak and would appreciate your comments and suggestions.My 20-ton pond has one 4-inch bottom drain and two 3-inch surface skimmers that connect to the sump. Pond flowrate is 10k lph. This flowrate can be maintained when the 2 skimmers are plugged up and the bottom drain left on its own. Likewise when the BD is plugged up and the skimmers left on their own. Knowing this, I've decided to plug my BD. This allows the filter to take in water from the pond's surface, which is generally cleaner, except for floating solid fish waste and leaves. These are easily filtered off by a coarse plastic screen. As a result, I have much cleaner pond water, as far as solids and fines are concerned, going into my bio-filters, where as usual, the regular nitrification cycle takes place. Less fines accumulating on the jap mats makes for less need for cleaning. The return water to the pond is less turbid as well.In shutting down the BD, I am letting solid wastes settle onto the center-sloped pond bottom. The plan is to do a daily flush of the pond bottom, thru the bottom drain.. Success is based on how well the flush cleans the pond of its solid wastes. The more solid waste settles on the pond center bottom, the more waste gets flushed. To aid in this, I plan to move my Matala diffuser from the bottom side to the center bottom so that it is above the BD cover. This should help draw wastes toward the center, a function previously being accomplished with the now-decommissioned bottom drain. If circulation is still found to be lacking by the presence of solid wastes around the pond, I will have to restore the TPR (tangential pond return).I have redirected return water from the filter fully to my waterfalls, thereby plugging the TPR, in order to increase oxygenation. This was brought about by my concern that plugging the BD might compromise top-bottom circulation of the pond, causing the bottom strata to be robbed of adequate dissolved oxygen (DO). I don't know if this concern is justified, as there is a Matala diffuser vigorously providing aeration which continually brings to the surface water from the bottom. By the way, pond height is 5 ft. at center sloping up to 4 ft. at the sides.I will be looking for signs of dead spots, circulation-wise, so I can make some more modifications to address this.In all this, I would have kept fish waste from needlessly compromising my biofilter's cleanliness and effectiveness, and from making my pond turbid. If needed, I will also use flocculants to aid settlement of fish waste.I would appreciate if you could voice your concerns as I am sure I'd have overlooked a few areas. Thanks.
    Hi Mike,

    I would discourage you from plugging up your only single bottom drain and relying on just surface skimmers because of the following reasons:
    1. Most of the waste will pass tru the bottom drain as there is continual suction
    2. In the event of BD shutdown, waste will not necessary travel near the bottom drain even with matala air diffuser positioned on top. Most waste will scatter at the bottom creating a false blanket of security that your filter is collecting less waste. Even if you restore the tpr and do daily flushing of the bottom drain, over time waste will collect at the bottom.
    3. Shutting down the bottom drain creates an uneven circulation of top to bottom water as water from top will not mix with water at bottom unless you have very vigourous air circulation which you don't have at the moment.

    Just a thought, have you ever considered reducing your use of EM1 bacteria to let the waste dissolve a lot longer. These kind of heterotrophic bacteria eats organic waste. Too much of this and PH will go down while waste will be harder to capture in the mechanical brush chamber as the waste are reduce easily and broken down. Take for example: if you take too much bacteria skim milk like Yakult, you process your waste better but the waste will be loose and easily dissolve in water. I mix my bacteria/vitamin supplement in the food that I give to my koi each day but I do this in careful measure amounts. Too much and the food will even begin to soften and liquify faster.

    With regards to the bio filters, I have discuss this matter with you. I believe it is inadequate considering the amount of food you give to your koi each day and with regards to your upkeep. If I were you, I would for temporary measure just cull or remove some koi to reduce the population until such time you decide to increase the size of your filtration or do more often upkeep of the filters. Less koi will mean less maintainance and better water quality.
    thefishlady likes this.

  3. #3
    Oyagoi yerrag's Avatar
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    1. Most of the waste will pass tru the bottom drain as there is continual suction.

    -Yes, that same waste is staying at the pond and not getting to the sump. The trade-off is that the biofilter does a better job since it gets less plugged up with fines. So I have better water quality as far as ammonia is concerned. Having solid waste accumulate at the pond bottom instead of the sump bottom puts waste closer to the fish, yet there is no increase in waste matter, when you think that the pond and filter is one connected body of water. If I were using UV and not using em-1 beneficial bacteria, the pond bottom would be filled with pathogenic bacteria and those bacteria would be in contact with the koi; those bacteria would otherwise be killed had waste been allowed to settle at the sump bottom by means of a bottom drain. Since I'm using em-1, having deactivated my UV unit, whether fish waste goes to the pond bottom or the pond bottom makes no difference, since the em-1 is keeping the waste from producing pathogenic bacteria.

    2. In the event of BD shutdown, waste will not necessary travel near the bottom drain even with matala air diffuser positioned on top. Most waste will scatter at the bottom creating a false blanket of security that your filter is collecting less waste. Even if you restore the tpr and do daily flushing of the bottom drain, over time waste will collect at the bottom.

    -The Matala diffuse is at the bottom, there is no purpose having it on top. There isn't any sense of false security as it is understood that the fish waste is kept from moving from the pond bottom to the sump bottom by closing the BD. The pond bottom will never be free from fish waste, with or without a BD. But frequent flushing ensures waste at pond bottom is kept from accumulating. But this is predicated on waste actually settling on the pond bottom, and accumulating near the bottom drain, where it can readily be flushed away. This is where there is concern, as over the weekend I dove in my pond and saw firsthand how much stuff is afloat and where there is settling, it is all over the pond bottom.

    After some careful consideration, I had to resort to going back to enabling the bottom drain. But I am doing it only temporarily to manage the situation and to refine my tweaks. In enabling the BD, I disabled the skimmers concurrently so that the suction thru the BD would be stronger. This was successful in reducing the fish waste strewn all over the pond significantly.

    At this point, I start to ask whether there is any point to this at all, as I am back to allowing some fish waste to be reintroduced to my biofilters, contaminating it and slowly plugging it and slowly rendering it less effective with denitrification. But since bottom-draining is only the second of a three-step cycle-time, the first being top-skimming and the last being flushing, I think its part-time nature allows at least for said contamination of the biofilters to be lessened. Still, even if this works, it is still rather complicated when you start talking of an n-part cycle. This is an affront to simplicity, and an invitation for Murphy to exert his law on me. So I'd need to choose whether to bottom-drain or top-skim, and my choice would ultimately depend on what workable and reliable tweaks I could bring to bear towards a better total solution.

    3. Shutting down the bottom drain creates an uneven circulation of top to bottom water as water from top will not mix with water at bottom unless you have very vigourous air circulation which you don't have at the moment.

    - It's a concern. Moving my diffuser towards the center will help a lot, but only partially. This may spell the doom of my tinkering. But before I give up on it, I have to research on employing natural vortex technology for help.

    Just a thought, have you ever considered reducing your use of EM1 bacteria to let the waste dissolve a lot longer. These kind of heterotrophic bacteria eats organic waste. Too much of this and PH will go down while waste will be harder to capture in the mechanical brush chamber as the waste are reduce easily and broken down. Take for example: if you take too much bacteria skim milk like Yakult, you process your waste better but the waste will be loose and easily dissolve in water. I mix my bacteria/vitamin supplement in the food that I give to my koi each day but I do this in careful measure amounts. Too much and the food will even begin to soften and liquify faster.

    I should actually ask you to try em-1 microorganisms on your pond to shake you of an unhealthy fear of living things that are microscopic, without which you are merely energy and ethereal:-) Actually, they are one reason my koi are not only healthy, but developing very well (the others are food and good water [which still needs to be improved]). Also, the waste matter will dissolve just the same without em-1. The difference will only be that without em-1 the results are smelly and pathogenic. But you are right in that excessive bacteria will cause loose stools. Too much probiotics and/or digestive enzymes and pfft...

    With regards to the bio filters, I have discuss this matter with you. I believe it is inadequate considering the amount of food you give to your koi each day and with regards to your upkeep. If I were you, I would for temporary measure just cull or remove some koi to reduce the population until such time you decide to increase the size of your filtration or do more often upkeep of the filters. Less koi will mean less maintainance and better water quality.

    Thanks for sharing Homer. So far my water parameters have been improving especially since you pointed out the reddening veins and the gill curls. My koi population, and some tilapia and mollies, need to be kept in check eventually. Boy, can those tilapia breed!:-) But population isn't an immediate concern. What is of more concern to me is to minimize fines without too much heavy work on my part. It is good to work hard at something, as long as you don't have to keep working hard at it forever. Reaping the rewards and enjoying the fruits, ahhh, priceless!

  4. #4
    Oyagoi yerrag's Avatar
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    Observations so far on my first week testing:

    1. DO levels are similar comparing pond water taken from pond surface and from deepest portion. This allays my fear regarding the pond bottom getting less oxygen.
    2. Pond water is clearer, although there would be white waste fibers seen suspended on the water column, especially in the morning. These would subside during the day and settle too the pond bottom. The improved clarity could very well be the lack of fines returning from the fiter, as there is no waste going into the filter with the bottom drain being plugged up. Although there is no lack of visible fines suspended in the pond, it does not reduce the visibility of the pound bottom, indicating less turbidity due to less fines being suspended.
    3. While as expected solid waste would accumulate at the pond bottom while the pond is on skimmer mode, I find it to be less of a concern. One positive is that the waste are not piling up to thick layers, as the pond bottom has a larger area than the sump bottom. The effect is salutary, as aerobic conditions prevail keeping assimilatory nitrification at bay. This keeps ammonia levels lower, and this is evidenced by the koi showing better shiroji, especially my shiro utsuri. The concern that my pond would become filthy with solid waste becomes less an issue, considering that I can switch to bottom drain mode (meaning bottom drain is enabled) to remove the waste accumulating at the pond bottom. Furthermore, I can flush the bottom drain to waste also.
    4. I find that the best time to use flocculants is when I switch to bottom drain mode. An 8-hour cycle in this mode with flocculants helps to rid the pond of suspended fines as well as waste from the pond bottom. This enables the accumulation of waste at the sump bottom, where it is pond-vacuumed subsequently.
    5. The use of em-1 microorganisms is having a benefit as it hastens the remineralization of the solid fish waste, keeping the fish waste from putrefying and producing ammonia, pathogens, and toxins. It helps to have plenty of oxygenation, to keep aerobic bacterial decomposition continually at work. While my pond is better maintained, it reminds me of food fish ponds ( e.g. tilapia) with no bottom drains being kept healthy with the use of bokashi balls, which are also made of em-1 microorganisms.

  5. #5
    Jumbo sacicu's Avatar
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    Quote Originally Posted by yerrag View Post
    Observations so far on my first week testing:

    1. DO levels are similar comparing pond water taken from pond surface and from deepest portion. This allays my fear regarding the pond bottom getting less oxygen.
    2. Pond water is clearer, although there would be white waste fibers seen suspended on the water column, especially in the morning. These would subside during the day and settle too the pond bottom. The improved clarity could very well be the lack of fines returning from the fiter, as there is no waste going into the filter with the bottom drain being plugged up. Although there is no lack of visible fines suspended in the pond, it does not reduce the visibility of the pound bottom, indicating less turbidity due to less fines being suspended.
    3. While as expected solid waste would accumulate at the pond bottom while the pond is on skimmer mode, I find it to be less of a concern. One positive is that the waste are not piling up to thick layers, as the pond bottom has a larger area than the sump bottom. The effect is salutary, as aerobic conditions prevail keeping assimilatory nitrification at bay. This keeps ammonia levels lower, and this is evidenced by the koi showing better shiroji, especially my shiro utsuri. The concern that my pond would become filthy with solid waste becomes less an issue, considering that I can switch to bottom drain mode (meaning bottom drain is enabled) to remove the waste accumulating at the pond bottom. Furthermore, I can flush the bottom drain to waste also.
    4. I find that the best time to use flocculants is when I switch to bottom drain mode. An 8-hour cycle in this mode with flocculants helps to rid the pond of suspended fines as well as waste from the pond bottom. This enables the accumulation of waste at the sump bottom, where it is pond-vacuumed subsequently.
    5. The use of em-1 microorganisms is having a benefit as it hastens the remineralization of the solid fish waste, keeping the fish waste from putrefying and producing ammonia, pathogens, and toxins. It helps to have plenty of oxygenation, to keep aerobic bacterial decomposition continually at work. While my pond is better maintained, it reminds me of food fish ponds ( e.g. tilapia) with no bottom drains being kept healthy with the use of bokashi balls, which are also made of em-1 microorganisms.
    Hi Mike,

    I am surprised that you have continued with your bottom drain plugging experiments.

    First of all, dissolve oxygen should be measured using a properly calibrated DO meter. A probe is lowered down the bottom to get the true reading.

    After one week i think you have proven that by closing the bottom drain, waste will settle all over the bottom part instead of being collected in the settlement chamber. That is the purpose of the bottom drain when it was invented many years ago. Almost all decent concrete ponds have bottom drains. My first pond had none and I had to painfully push away any waste that may settle by stategically placing several smaller submersible pumps to suck the waste towards the filter. Overtime, i realized how difficult it was to still have a clean bottom despite the best efforts. Having bottom and side drains is now a blessing as I can remove thru gravity heavy settling waste thru the BD and floating waste tru thr skimmer and the side drain. With a fast turnover, most waste will be trapped in the settlement and mechanical area. Daily 5 minute flushing keeps the system working perfectly everyday. It may be a chore to some but I find the daily flush my morning exercise. If ever I am busy or lazy, my maid would take care of it. Water is very clear and healthy without use of any UV. No need to use any flouculants, baking soda, etc. Water TDS is at a constant 85ppm, nitrates is always at 10. Temperature now at a constant range of 24.5 to 25.8c despite the hot summer day now. Water change is 5% a day . Koi growing very well while color is able to catch up and improve. Feeding is just enough to grow the koi at a regulated pace without causing harm to the koi or overloading the filter.

    I cannot imagine what will happen if I plug my bottom drains and rely on just my side drain and surface skimmer.

    I am not discouraging you to stop your experiment. Maybe in your system and setup it could work. If it does it would be unique.

  6. #6
    Oyagoi yerrag's Avatar
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    First of all, dissolve oxygen should be measured using a properly calibrated DO meter. A probe is lowered down the bottom to get the true reading.
    If money were falling like manna, I would take that advice. My test strips from Salifert will do the task I need it to fill. I'm simply comparing surface water and bottom water for DO differences. I'm not looking for accurate values. For that, the test strips give me a consistent ballpark result.

    Overtime, i realized how difficult it was to still have a clean bottom despite the best efforts.

    A clean immaculate bottom is nice but not necessary unless it is a requirement for esthetics. Even so, with all the surface bubbles in a pond, who would notice. We may mind, but would the fish? So long as water is not laden with dissolved solids (ammonia, nitrite etc.), is well-buffered, has sufficient DO, and is not teeming with pathogens, and not turbid, what's not to like? Aren't the koi developing well, looking nice, swimming well, eating well, and well-socialized?

    With a fast turnover, most waste will be trapped in the settlement and mechanical area.

    Not quite. Too high a turnover rate risks having too short retention time in the sump for the solid waste to settle. Many ponders overlook this bit.

    Daily 5 minute flushing keeps the system working perfectly everyday. It may be a chore to some but I find the daily flush my morning exercise. If ever I am busy or lazy, my maid would take care of it. Water is very clear and healthy without use of any UV. No need to use any flouculants, baking soda, etc. Water TDS is at a constant 85ppm, nitrates is always at 10.

    Your ERIC system makes that possible. And I'm happy that you are contented with it. Last time I checked with you, you were content with values of 40 ppm with nitrates. What changed?

    Temperature now at a constant range of 24.5 to 25.8c despite the hot summer day now.

    Well done. My pond is at 29c. Time to put back the shade sail. Plus I'm changing my food mix to accommodate the higher temps.

    I cannot imagine what will happen if I plug my bottom drains and rely on just my side drain and surface skimmer.

    Me neither. But I'd advise you to regularly flush the bottom drain if you take that route. That's what I indicated.

    I am not discouraging you to stop your experiment. Maybe in your system and setup it could work. If it does it would be unique.

    Thanks Homer. Different strokes for different folks. And we learn a lot from each other's mistakes as well as successes. Cheers!

  7. #7
    Jumbo sacicu's Avatar
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    Quote Originally Posted by yerrag View Post
    First of all, dissolve oxygen should be measured using a properly calibrated DO meter. A probe is lowered down the bottom to get the true reading.
    If money were falling like manna, I would take that advice. My test strips from Salifert will do the task I need it to fill. I'm simply comparing surface water and bottom water for DO differences. I'm not looking for accurate values. For that, the test strips give me a consistent ballpark result.

    Overtime, i realized how difficult it was to still have a clean bottom despite the best efforts.

    A clean immaculate bottom is nice but not necessary unless it is a requirement for esthetics. Even so, with all the surface bubbles in a pond, who would notice. We may mind, but would the fish? So long as water is not laden with dissolved solids (ammonia, nitrite etc.), is well-buffered, has sufficient DO, and is not teeming with pathogens, and not turbid, what's not to like? Aren't the koi developing well, looking nice, swimming well, eating well, and well-socialized?

    With a fast turnover, most waste will be trapped in the settlement and mechanical area.

    Not quite. Too high a turnover rate risks having too short retention time in the sump for the solid waste to settle. Many ponders overlook this bit.

    Daily 5 minute flushing keeps the system working perfectly everyday. It may be a chore to some but I find the daily flush my morning exercise. If ever I am busy or lazy, my maid would take care of it. Water is very clear and healthy without use of any UV. No need to use any flouculants, baking soda, etc. Water TDS is at a constant 85ppm, nitrates is always at 10.

    Your ERIC system makes that possible. And I'm happy that you are contented with it. Last time I checked with you, you were content with values of 40 ppm with nitrates. What changed?

    Temperature now at a constant range of 24.5 to 25.8c despite the hot summer day now.

    Well done. My pond is at 29c. Time to put back the shade sail. Plus I'm changing my food mix to accommodate the higher temps.

    I cannot imagine what will happen if I plug my bottom drains and rely on just my side drain and surface skimmer.

    Me neither. But I'd advise you to regularly flush the bottom drain if you take that route. That's what I indicated.

    I am not discouraging you to stop your experiment. Maybe in your system and setup it could work. If it does it would be unique.

    Thanks Homer. Different strokes for different folks. And we learn a lot from each other's mistakes as well as successes. Cheers!
    I am no sure how you are able to accurately measure dissolve oxygen using strip at the bottom of the pond. Taking water at the bottom and raising it up exposing the water to atmosphere and therefore dissolve oxygen. The salifert test cannot be use to take dissolve oxygen reading at the bottom of the pond. The fact that dissolved oxygen meter is the standard being use and not the salifert test kits speaks for itself.

    With regards to nitrate at 40ppm is not a problem is something I still agree at simply because I have seen show koi raised at that nitrate level and they skin still looked very good. I have a 10ppm nitrate because of my system in place and I feel that at 10ppm nitrate level this leaves me a lot of room from 40ppm.

    If one prefers a fast turnover, it should suit the filter system in place. No point of having a fast turnover if the waste will return to the pond either by failure to do regular maintenance based on water temp, feed rate and number of inhabitants or if the filter is not designed for it. In my case, I have a fairly good filter setup whereby most(99%) of waste gets trapped in the settlement and brush chamber. My daily flush does help a lot and also the the design of the filter.

  8. #8
    Oyagoi yerrag's Avatar
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    Quote Originally Posted by sacicu View Post
    I am no sure how you are able to accurately measure dissolve oxygen using strip at the bottom of the pond. Taking water at the bottom and raising it up exposing the water to atmosphere and therefore dissolve oxygen. The salifert test cannot be use to take dissolve oxygen reading at the bottom of the pond. The fact that dissolved oxygen meter is the standard being use and not the salifert test kits speaks for itself..
    There is an invention called a syringe. You dive in the bottom, get a sample of water. Bring it up. And do the test. The fact that a DO meter is the standard doesn't mean there is no other way to do it. A Salifert test does the job I need it to without unnecessary spending. If you want it 'by the book' and want to be anal about it, it is your choice. Plus, you're not reading my answer enough. I'm not looking for accuracy here.l'm COMPARING surface readings with bottom readings. If the surface water is reading higher DO, there is a problem. If there isn't, there's no problem. If the Salifert test strip is not accurate but is consistently off, it is precise enough to be used to compare. Understand that accuracy and precision are different animals. If you can't make that distinction, let me know and I can explain to you.

    Remember, Homer, that your being right on the way you design and operate your pond doesn't preclude others being right about the way they run and operate their pond. There are different ways about it. But your insistence that surely DO would suffer in my pond just because I'm not doing it your way is rather presumptuous. And what if I do have a DO meter to prove my case, what new nitpick would you bring up?

  9. #9
    Jumbo sacicu's Avatar
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    If you dive in the pond, do you not introduce a big amount of air into the pond since your mass is much bigger than the koi? If you use a vacuum to suck water and then release the water, do you not introduce air molecules in the water? If the water temperature is lower at the bottom than at the surface and you got the same reading, is the oxygen saturation same?
    I am not saying the chemical test for dissolved oxygen is not good. Its is used in aquariums where the air pumped out as compared to the body of water is much higher.
    I am just not convinced with the use of the salifert test kit in a big volume of water. A properly calibrated dissolve oxygen meter though gives a more accurate reading and if does show there is no difference in water temperature and dissolve oxygen at the surface and bottom of the pond when there is no bottom drain and just one diffuser then I am proven wrong.

  10. #10
    Oyagoi yerrag's Avatar
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    There you go again with your nitpicking. Seriously, my diving in would have that significant an effect? I'm not diving in like I'm intending to create a splash to frighten my koi. It makes me laugh now that I see how hopelessly argumentative you are to the point of asphyxiation. Now I am making this as objective as possible, and welcome more enlightening comments than that. Calibrated meter for what? You have one? Someone lend me a hand here and explain to Homer why you don't need a calibrated DO meter for what I'm doing. It's not getting through to him.

    I'll try again. When you compare temperature inside and outside an air conditioned room, yoiu get one thermometer and take readings. The thermometer will tell you that the room has a COLDER temperature.Do you question that? No. Because calibrating the thermometer isn't necessary, for obvious reasons. You really don't care if the thermometer is so accurate, and by accurate I mean that it will read 0°C when it is 0°C. It can read 1°C so long as it is consistently off by the same amount. So, the thermometer will read 26 inside the room, and 31°C outside. While in reality it is 25.0 and 30.0°C respectively. Still, you can make a conclusion that it is colder inside than outside the room. YOU DON'T NEED A FREAKIN DOPPLER STATION TO TELL YOU THAT.

    Now, please spare me the retort that this isn't a perfect analogy.

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    Replies: 2
    Last Post: 06-14-2006, 07:44 PM
  5. Bottom Drain
    By jjkon in forum Main Forum
    Replies: 2
    Last Post: 06-14-2006, 07:44 PM

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