Still struggling to keep water clear

Discussion in 'Introductions' started by hdavid44, Mar 17, 2012.

  1. hdavid44

    Waterbug

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    At 25 cents/kwh a better pump would pay for itself in less than 2 months, maybe less than a month.

    I still have no idea idea what you mean by "algae driven cloudiness". I can only tell you UV will clear green water. If the cloudiness is coming from something else a UV won't help.

    Probably not sterilizer, maybe clarifier. These things are rated by flow...1" pipe has little meaning. Pump flow rate is what has to be known.

    UV filters are rated by the manufacturer for different flow rates and pond sizes. For example, a 6000 gal pond is unlikely to be cleared by a 9, 19, or 35 watt UV. Aqua UV for example requires a 40 watt unit to operate as a clarifier and a 120 watt unit to act as a sterilizer. Sometimes you can get away with less, sometimes you can't. Depends on water conditions. What the manufacturer specs is generally their best guess for general pond conditions.

    In all cases these need to run 24/7. Turning them on and off just allows the algae time to reproduce so there wouldn't generally be much point to running it at all.

    In many cases a UV can be turned off a couple of weeks after the water clears. Macroalgae and/or bacteria can then keep the microalgae from coming back. These things are natural, you don't have to buy macroalgae or bacteria. This is hit and miss but worth a try. Turn off the UV and see if the green comes back. You can repeat the process and keep trying to see if the water will stay clear. When this works water can stay green free for many months, even years.

    To summerize...
    For a 6000 gal pond a modern 200 watt pump would push about 3000 gph, a 40 watt Aqua UV max flow is 2900 gph. Running 24/7 would cost $1.44 per day at 25 cents/kwh. It can be that simple.
     
    Waterbug, Jun 11, 2012
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  2. hdavid44

    hdavid44

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    Waterbug: Thanks for the good info.

    The UV light in-line with my glass bead filter and high wattage pump does a good job of clearing green water when I leave it on full time. I just fired it up and had it going for less than two days and it has already begun clearing.

    Here is my problem: I believe I need a high wattage pump because ;

    1. The filter intake is 3 feet below grade and the top of the waterfall it feeds is 6 feet above grade. Total head -- 9-10 feet
    2. The intake is located 40 feet from the pump horizontally and the feed to the waterfall adds another 20 feet. Total 60 horizontal feet, equivalent to about 9 feet of head.
    3. So total vertical head is about 20 feet and my current pump does the job.

    However, the pump draws 11 amps @ 120 V which takes 32 Kwh per day. At about 18 c/kwh we have about $6/day.

    If not for this cost issue, I could run this setup 24/7.

    Hence my quest for a more efficient pump that has the necessary capacity.

    Which triggered the thought that I might be able to put a UV light in-line with the pump that moves pond water into my big 2000 Gallon bog. That line is 1" diameter.

    The simplest solution would be to either move the existing UV light -- 2" PVC connections -- from the big pond filter and put it in-line with the bog pump with appropriate adapters to fit the 1" line.

    My question then boils down to: Will the much reduced flow rate of the bog pump coupled with a fairly big wattage UV light do the trick?

    Does the flow rate matter much when it comes to sterilization? As long as the water flows at some rate and the UV zaps the algae should this not do the trick??

    I will go to the pond next weekend and get the UV bulb size and the bog pump capacity.

    Thanks again for the information.

    harry

    PS: I would be quite happy if the 200 Watt pump you reference could push water 10 feet up and 60 feet across. Hence my interest in just locating a UV light closer to the pond -- in between the pond and the bog, minimizing both horizontal traverse and vertical head. At that point I either try to use the existing bog pump and put the UV light in-line or buy another pump of capacity sufficient to move water only 5-6 ft vertical and 15 feet horizontal which is much less that the load for the pump attached to the current pond filter location feeding the waterfall.

    So they sell combination UV lights with attached pumps that I could try?
     
    hdavid44, Jun 11, 2012
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  3. hdavid44

    hdavid44

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    I found this submersible 40 Watt UV Sterilizer for around $200. I am considering putting it in-line with the bog pump to sterilize the water on it's way from the pond to the bog.

    The 1 1/2 inch inlet/outlet should easily connect to my 1" flexible corrugated hose going from pump to bog...

    Any thoughts.

    harry
     
    hdavid44, Jun 12, 2012
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  4. hdavid44

    Waterbug

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    OK, understood.

    OK, I understand. Good to see your electric has dropped from 25 to 18 cents. That does seem more inline with what I'd expect in CT.

    Two issues...
    Your calculation on loss of head for 60' of horizontal run seems way, way off. You've unable to give any info that would enable even a rough estimate so here's just an example, a 60' horizontal run of PVC at 3000 gph would have the following head loss:
    3" pipe = 0.4" head loss
    2" pipe = 2.8" head loss
    1.5" pipe = 11.5" head loss
    1" pipe = 82.6" head loss
    3/4" pipe = 335" head loss (basically the pump stops working)

    Even a 1" pipe wouldn't be 9' of loss. But yeah, if you're paying an extra $1200 a year to save replacing undersized pipe with $40 worth of properly sized pipe I think I'd look at replacing the pipe.

    Second, your focus on electric is pretty meaningless. The amount of electric only tells you how much you pay, not how much water is being moved. Without knowing basic info like pump GPH, size and type of pipe and UV flow rates you're totally in the dark and guessing.

    No way to tell as you don't seem to know pump or UV flow rates or you're not sharing. I see you've been asked the question in the this thread but never responded at least that I could see. Kind of hard to help.

    There's the issue. All UV filters are both a sterilizer and clarifier. Got it? Not some, not this or that model. All. Every single one. Manufactured or home made. All.

    The only difference between a UV being a sterilizer or clarifier is the flow rate. Turn the flow down and at some point 99.9% of living things will be killed in one pass...that's a sterilizer. To clear green water it is not necessary to kill 99.9% of everything, microalgae is much easier to kill than some bugs. So water flow can be increased and then that exact same UV would be called a clarifier as long as water flow is still low enough to kill all microalgae for a given pond size. If water flow is increased further the UV does nothing and is called worthless.

    I think you're misunderstanding some things, but I'm not sure. Head is measured from the pond's surface to where water exits the pump pipe. If the pump is at the bottom of a 3' deep pond and pumps to a falls 4' above the pond surface the head is 4'. If the pump is at the bottom of a 20' deep pond the head is still 4'.

    It doesn't matter how close or far the UV is from the pump, the flow is the same throughout the pipe. Unless the UV is way off on it's own for no apparent reason and you can reduce the total length of pipe. Then you can gain a little. But with proper sized pipe you'd be gaining fractions of an inch of head.

    They do. I personally don't like them because it can be difficult to adjust the flow. The spec manufacturers give for clarifier is just an estimate for median ponds. Often water conditions make the UV less effective and the flow has to be turned down.

    Saving money...
    You're focused on using your 11 amp pump for some reason while at the same time being concerned about electric costs. Those 2 issues will never resolve themselves. There are only 2 ways to reduce electric cost. One, call the electric company and negotiate a lower rate...good luck. Two, switch to a pump that uses less electric.

    A 60 watt UV connected to a 3000 gph 200 watt pump will clear a 6000 gal in less than a week. That's the bottom line. A 3000 gph pump for a 6000 gal is probably OK fish load wise, but you'd have to check that.

    A waterfall is an entirely different issue. That's almost purely for aesthetic reasons...it is not needed to keep a pond clear or fish alive. If you want a tall falls with a lot of flow that costs money. A 4' head you lose about 1/3 of the pump flow (depends on kind of pump). But it could be turned off whenever you like, it's only for your enjoyment. There are other benefits to waterfalls, like bio filtering...but that's another subject.

    O2 is added to the water by stirring the water. Waterfalls actually do a poor job of this. You will get more O2 by just having the pump stir the water. 0 head = more gph = more stirring.

    You can also use air pumps instead. Although people think it's the bubbles it's really just the bubbles pushing water to the surface for gas exchange that make these work. Air pump use less electric to move the same amount of water as a water pump. That's why air pumps are used, cost saving. You could also choose to only turn on the air pumps at night, or when the water is warm.

    For a UV to work it has to run 24/7, but maybe not forever. You also want to make sure it's installed correctly. They're often installed upside down and air gets trapped inside and they don't work as good.

    So you could greatly reduce electric costs and increase water quality by selling the 11 amp monster on Craig's List and buying 2 or 3 pumps that solve specific needs. Each can be much lower power and only be used when needed.

    I do think you're on the leading edge of what many more people will start to be concerned about in the future. Right now most people are OK with wasting $10 or $20 a month on electric. Too little an amount to bother with. But in the years to come, as electric gets into the 50 cents to a dollar range, that burning of $10 and $20 bills is going to be $50 to $200 a month up in smoke. Then there's going to be a lot more interest in how much electric a pond actually needs to use and "saving the planet" will go main stream.
     
    Waterbug, Jun 12, 2012
    #64
  5. hdavid44

    hdavid44

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    Waterbug: Thanks for burning midnight oil -- at midnight -- to comment on my pond clarity issues.

    Let me address some of your comments.

    1. My focus on the existing pump stems from my attempt to identify a higher efficiency replacement. I have 2" flexible hose from the pond bottom to the pump, thence via 2" rigid PVC to a glass bead filter, in-line UV light and back via flexible 2" hose to the waterfall. Some sizing material I had read suggested that every 10 feet horizontal traverse adds 1.5 feet to head loss. Perhaps I read this wrong and it may have been 1.5" of headless per 10 feet??!! In any case, from pond water top level to waterfall top level is about 10 feet.
    If I go by your numbers for a 3000 gph flow and a 2" pipe I should add a 2.8" head loss for 60 horizontal feet?? Add that to the approx 10 feet of head and I have a much lower head loss.
    (I note and accept your correction that head loss is calculated from the top of the pond level, not the intake point)

    How can I get the gph for my pump when it depends so much on the waterfall vertical height above pond level? I shall focus on finding a pump that can push up a 10 feet head at about 3000 gph. Perhaps I can find a high efficiency unit that can do this. Please confirm this understanding -- that I can basically ignore the horizontal traverse for a 2" pipe and size the pump for flow rate and about 10 feet of head.

    Question: Why should I care about flow rate? Other than aesthetics for the waterfall "sturm und drag" can I not look for a flow rate to achieve water turnover about every 2-4 hours? Then my 3000 gallon (approx) water capacity can be accommodated by a 1000 gph pump at 10 feet of head??

    2. UV Light capacity. Bulb capacity interacts with flow rate to zap algae? So algae killing effectiveness depends on bulb power, flow rate and the rate of algae growth?
    3. Since the waterfall function is purely aesthetic and it is the UV that is doing the algae killing job, I was considering separating the two roles and just keeping the existing pump for occasional waterfall use and find alternative UV algae killing options?
    4. That is what leads me to consider the flow between the pond and the bog. Again, I don't have the pond-to-bog pump capacity -- I will get it next weekend along with the existing UV bulb wattage-- but if I could insert an adequately sized UV light in-line with the pond-to-bog water flow I can procure a more efficient pump -- even the existing one if it is big enough -- and put the UV light in-line. No significant head loss from pond surface to both wall height -- about 24". So how do I size the UV light capacity/flow rate equation? When I know the existing UV light capacity which does an adequate job when left to run 24/7 through the 2" pipe and big pump -- that should give me a baseline for the UV wattage.
    5. I have an aerator in the pond running 24/7 with three submerged discharge devices. So I get aeration this way.
    6. Regarding future energy costs. I have some contrarian thoughts. If tree huggers dominate the discussion then all carbon derived energy -- and even nuclear -- will rise in cost to discourage use and to make wind/hydro/algae (!!) sources more competitive. On the other hand, if fracking continues and natural gas use for electricity generation grows significantly then electric energy costs will decline. Gas now costs $2 per million BTU's -- this may go up. Oil costs $3/gallon and generates about 140,000 Btu's so that cost is $21/million Btu's.. Can this 10{1 cost advantage be right??

    Anyway, thanks for your time and helpful advice. I will get back with info on the existing pump size, model, etc and UV light wattage, and waterfall head.

    Harry
     
    hdavid44, Jun 12, 2012
    #65
  6. hdavid44

    Waterbug

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    That doesn't sound good. Depending on length that could really constrict flow. Friction loss on the pressure side of the pump is one thing, on the suction side it's a different deal, way worst.

    For rigid PVC yes. Flex is different.

    Still don't know where this 10' head is coming from...thought the waterfall was 6' above grade...the pond surface is 4' below grade?

    Manufacturers test GPH at different heads and publish it. If you can't find it you can add a flow meter or test with a 5 gal bucket and a stop watch.

    Yes. A couple of inches of head loss isn't that big a deal imo.

    For the waterfall it doesn't matter. Flow rate tells what size pipes to use, head loss, how a UV is added. That's the technical end of things. How much movement is needed in the pond is more of an art and how you want to keep fish. High end keepers like more movement, more O2, more fish growth.

    You've got it.

    That'll work. I have no idea why you would keep that 11 amp electric hog...unless it's pumping something like 18,000 gph...when you sound like you're concerned about electric cost. I mean sure only running it for 8 hours a day costs less...but that just means it would take 6 months for a new pump to pay for itself instead of 2 months.

    My head is spinning a bit...not sure if you're over thinking this because I can't really follow...here the easy way...when you shop for a UV it should give and a pond size. That's how you size the UV. You can get a unit that can handle a little larger pond if you like.

    Next the UV builder will define the flow rates, hopefully for both sterilizer and clarifier, but just clarifier will work. With that info you'll know what size pump to get.

    Next you can figure the pipe size based on the flow rate. You do that by checking online friction loss calculators. You don't want the pipe so small that you're losing like 12" or more of head.

    When you install the UV make sure you add a ball valve between the pump and UV so you can turn down the flow if the pond isn't clearing. If you want you can also add a bypass pipe so you're still getting your moneys worth flow wise, but that's optional.

    Sounds very good.
     
    Waterbug, Jun 12, 2012
    #66
  7. hdavid44

    hdavid44

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    Waterbug: hallelujah!!! All is revealed...

    I checked the UV light and it is a pricey ($800 approx) Zapp Pure 5, 36 W stainless steel device that is in-line with the pump. I spoke to the Company and they said that there is no minimum flow rate required to protect the device.

    Therefore I would like to disconnect the Zapp Pure from the existing pump, move it to the bog and install it in-line with the smaller pump pushing water from the pond to the bog.

    I still did not check the flow rate of this Laguna pump but it seems to fill the 1000 gallon bog in about one hour.

    I can save the original glass bead filter and pump to move water to the waterfall for display purposes.

    What think you?

    Harry

    PS: The vertical head from pond surface to waterfall top is 8 feet....
     
    hdavid44, Jun 13, 2012
    #67
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