In-well Chlorination?

Discussion in 'Pumps and Tanks Well Forum & Blog' started by kplank, Jul 6, 2010.

  1. kplank

    kplank New Member

    Messages:
    6
    Location:
    Kansas
    I have a shallow well (40', 1 hp 18 GPM pump set at 30', static water level at 9'). This well supplies my house as well as a 3.5 ton open loop geothermal heat pump. The heat pump draws 6 GPM while running. I have to clean the sediment filter and clear plastic water flow meter regularly as they quickly (within a couple weeks during very hot or cold weather) become encrusted with a reddish brown deposit Water has been tested to have 0.1 PPM iron.
    I pulled the pump last year to inspect it and found a lot of the same reddish brown deposits around the pump inlet partially blocking it.
    I have replaced some of the copper plumbing and found the same deposits in the pipes, in some cases nearly a 1/4 inch thick in some of the 3/4 inch copper.

    I am looking for some expertise as to how to best solve this problem.
    An iron filter would probably not be too useful due to the high volume of water for the heat pump.
    I've been told a new well is my best option, but it is not assured of solving the problem due to the shallow water table.
    The only other option I have been told about is to install a dry pellet chlorinator at the well head followed by a whole house backwashing sediment filter. As I understand it the chlorinator causes the iron to precipitate out, the well services as the retention tank, and the sediment filter removes the chlorine and precipitated iron.

    Any thoughts as to which option might be best? I really haven't heard much at all about how well the dry pellet chlorinators work for situations such as this.
  2. nhmaster3015

    nhmaster3015 Master Plumber

    Messages:
    836
    Location:
    The granite state
    I foresee many future problems arising from chlorination equipment and back wash filters if your iron is that bad, but drilling a new well may make no difference either. Kind of a rock and a hard place scenario. I think I would go with injection and filtration, but......... your GW Heat pump requires a specific flow so make sure the backwash filter will handle the volume. Beware also that chlorene is particularly hard on pumps and anything else with rubber seals
  3. kplank

    kplank New Member

    Messages:
    6
    Location:
    Kansas
    Doesn't injection require a retention tank? Which if the heat pump is drawing 6 GPM, would have to be pretty big?
    I really didn't think the iron was too bad at 0.1 PPM. Maybe it's just the shear volume of water going though the heat pump though. With all the geothermal units installed; granted, maybe not a large percentage would be open-loop; I would assume this would be a somewhat common issue.
    I suppose I can keep cleaning the sediment filter and flow meter every two weeks, and pull the pump once a year, I would just hope for a better solution.
  4. Gary Slusser

    Gary Slusser That's all folks!

    You probably have IRB (iron reducing bacteria). have you noticed any clear to redish brown slime anywhere in the filters, toilet tanks etc? If so it IRB. They love to live where the velocity is highest, like the holes in the foot valve inlet screen or the inlet screen on a submersible pump which they will block solid soon enough. they also will live in all the cold water plumbing and the water heater. They can cause the amount of ferrous iron to fluctuate widely. You have to kill them to get rid of the problems they cause. They are harmless to humans and animals.

    A pellet dropper on the well runs when the pump comes on and it drops one or more pellets every one or X pump runs. They have a wide range of dosage. They usually work very well and as time goes by you must adjust the dose and it gets down to very little chlorine use.

    They must be installed per the instructions or you run a risk of damaging the pump or cable etc. and even then they can anyway but that is rare IMO,

    The chlorination will cause dirty water due to killing the IRB and oxidizing iron into rust.

    A new well is not an option IMO because there is no guarantee of an improvement in your water quality. Bacteria of many types live below ground in or out of water. Reducing types of bacteria are actually groups of various types of aerobic and anaerobic bacteria.
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