Adjusting BIRM Backwash Cycle for Well-Limited Water Flow

Discussion in 'Water Softener Forum, problems, installation and r' started by JVance, Feb 10, 2013.

  1. JVance

    JVance Homeowner

    Messages:
    28
    Location:
    Johns Island, SC
    For iron filtration, I'm using a 1.5 cuft BIRM filter and Fleck 7000sxt valve. Lately, my well/pump has been running low on pressure towards the end of the backwash/rinse cycle, and I am concerned I may no longer have the flow necessary to properly backwash the filter. Can I shorten the duration of the cycle(s) and increase the frequency so that I do not overdraw my well and therefore maintain sufficient flow/pressure during the entire backwash cycle?

    Currently, the valve is set on the dF2b cycle, 14 minutes for 1st backwash, 10 minutes for draw, 0 minutes for 2nd backwash, and 12 minutes of fast rinse. The frequency of backwashing is once every 3 days. We have a shallow well and live on a sandy island. Our pump and storage tank (~120 gallons) normally maintain 45-55 psi of pressure through all our household water use; but, lately, towards the end of the backwash, the pressure dips around 30 psi and water flow through the pump sounds intermittent.

    I'm not opposed to reducing the cycle duration and backwashing every day if this prevents overdrawing the well and losing flow at the end of a cycle, but -being a novice- I am not sure whether a short-duration/frequent backwash would be effective.

    Any advice that may point me in the right direction, or am I simply at the mercy of our ever-changing water table?
    Thanks in advance!
  2. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    4,150
    Location:
    NW Ontario, Canada
    Given that you are on sand, enlarging the well would probably be your best remedy. Can you go deeper or would you need to increase the diameter to increase the reserve capacity? Maybe driving multiple sand points would be easier.

    What I do with my iron filter is to do manual backwashes periodically. I raise the system pressure to 80 PSI, temporarily open up the micronizer bypass to allow the pump to sustain 80 PSI, and manually turn the flow on and off in bursts to shake up the media.
  3. JVance

    JVance Homeowner

    Messages:
    28
    Location:
    Johns Island, SC
    If I stick with the shallow pump, multiple well points might be the most economical solution. I do know that there are some high-producing deep wells on the island, but are typically for agriculture.

    I know little about this Fleck valve, but I understand the dF2b setting is designed for water softener systems. If I stick with the automatic schedule, do I need the draw and rinse cycle with a simple media filter set-up? Or do they contribute to agitating and settling the media? The settings I posted above were advised by the vendor (affordablewater.us), so I haven't questioned them until now.

    In any case, your backwash procedure is simple. So, I will probably give that a shot until the well production picks up.
  4. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    4,150
    Location:
    NW Ontario, Canada
    I'm not familiar with that Fleck but IMHO the brine draw cycle is a waste. I cannot see how a forward rinse would do any good. Only the backwash and the fast rinse/pack are of value. The pack is especially important as it will determine how well it filters so if you are out of pressure by then you probably are not getting a good pack. If you can see the discharge to the drain, you should be able to determine how long the backwash needs to run for.

    Both my softener and iron filter use the same simple mechanical clocks with cams but the cams on the iron filter are very different and do nothing during the brine draw and refill cycles.
  5. JVance

    JVance Homeowner

    Messages:
    28
    Location:
    Johns Island, SC
    Thanks for the info. After some Google searching, I found a different vendor whose set-up instructions were posted online. With BIRM, they suggested only the backwash and rapid-rinse settings, each for 10 minutes. From your recommendation, I should set the duration of the backwash on when the backwash clears out; should the rinse be equal in duration? Or is the rinse time dependent on the volume of the media?

    In any case, eliminating the draw should reduce over 25% of the water use, and reducing the backwash and rinse from the current settings even more. That alone might allow the cycle to finish with enough pressure and flow to pack the media.
  6. ditttohead

    ditttohead Water systems designer, R&D

    Messages:
    1,906
    Location:
    Ontario California
    You have an odd situation. It sounds like someone has used a softener valve instead of a filter valve. The filter valve has a different piston, no brine valve, and the injector is replaced with a plug. You can not reprogram the valve to a filter since these pistons have different homing positions.

    I would reprogram the valve for a 10 minute backwash, 0 minute brine and rinse, and a 4 minute fast rinse. The fast rinse helps remove the dirty water that was used for backwashing and replaces it with filtered water. The fast rinse can be reduced to the tanks water volume at a minimum, on a birm system that is usually around 4 minutes. You can reprogram the valve to a ST1B (single backwash) and it will be fine. The softener piston does fine for a filter valve, but the standard piston for backwashing has a limited backwash rate. How big is your Birm tank?
  7. JVance

    JVance Homeowner

    Messages:
    28
    Location:
    Johns Island, SC
    I believe you are correct. When I initially attempted to program the valve in the Filter setting, the valve would stay open (backwash) when at rest, and would close (stop backwash) when the backwash cycle would activate.

    Fair enough!

    The tank is 10" in diameter, 54" tall. (~18 gallons)
  8. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    4,150
    Location:
    NW Ontario, Canada
    My iron filter has a much faster backwash rate than my softener. Makes sense since the media is much heavier. Even at that I like to raise the pressure for a manual backwash to really shake it up. On my system the backwash rate is very much dependent on pressure so higher pressure means a more aggressive backwash. Likewise for the pack.

    My iron filter is in a conundrum in that the miconizer limits the GPM but then more GPM is needed for a good backwash. If I open the bypass on the micronizer to get more GPM, I get less aeration and subsequently less iron removed. If I close the bypass more, I get more aeration and more iron removed but not enough GPM for a good backwash.
  9. ditttohead

    ditttohead Water systems designer, R&D

    Messages:
    1,906
    Location:
    Ontario California

    Actually, on a Fleck or Clack and several other controls, pressure has very little to do with the backwash. Higher pressure will make more noise. The flow control regulates the water flow to the same amount regardless of pressure (within reason of course). So regular pressures of 25-125 will backwash the same amount of flow. The other factor that affects backwash is water temperature.
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