Sounds like you have done your research and are on the same page as everybody else in the industry and the world... -1. Every other day should be adequate, many people use that water for irrigation so the water is not "wasted". Filox-R, Pyrolox, etc should be backwashed according to the manufacturers recommendations, but the water temperature is often neglected to be considered. For many medias, water temperature is not as critical. For Filox/Pyrolox, it is a very important part of the calculation. Congrats on a successful install.
Regarding smaller pumps handling Filox, it is common to use 2 smaller systems so the regeneration backwash rates can be accomodated.
1. I don't think I said anything about flowrate being diminished during repressurization.
Originally Posted by traderyoda
2. I don't think I am assuming a constant flow rate "from the pump"--I do think I am assuming a constant flow rate to the backwashing filter equal to the flow control button rating but other than that the rates in the sample calculation are average flow rates.
3. I think the variation you see in current to the pump is the result of varying pressure as the pressure tank cycles between the low pressure cut in and the high pressure cut off. I believe that flow from the well pump does diminish as the pressure in the pressure tank rises.
4. When you say the "tank cycles - it cycles every 80 seconds during the backwash" what is the time interval measuring--pump on to pump off or pump on to pump on?
As a final point--it seems you have plenty of pump capacity to backwash at 14 gallons per minute. As you said the fact that the pump is able to refill the pressure tank during a backwash indicates the pump output is greater than 14 gpm. I was only trying to point out that I didn't believe the calculation procedure you used to determine AVERAGE pump output during a pressure tank refill was correct and to provide you with the correct procedure.
Traderyoda... dittohead says I know nothing about this stuff and he hasn't said a word to correct any of your assumptions about the well, pump or pressure tank and its ability to successfully backwash heavy minerals except to say all's well but... two filters would be better.
If I'm understanding you, that 47 gallons is greatly reduced by the volume of captive air that becomes compressed air when the pump is turned on. Usually that volume amounts to about 60-70% of that 47 gal tank and if it is an air over water tank, such as a galvanized tank, it can be more than 70%.
dittohead needs to expand his thinking out of his southern California climate and think about the rest of the continent. Or at least the 80%+/- part of the US where well water temps are consistently below 50f. And that irrigation doesn't work in that area for about 6-9 months a year and that for many months the temp is below freezing. So there has to be another place the drain line water has to go than outside above ground or even below ground but above the frost line.
Usually that is into an onsite septic system and in many cases a sand mound type. Your 14 gpm for 15 minutes is a lot of water and personally I would not want that much going into my septic system, and then every other night. dittohead seems to think that isn't a problem but your customer may differ and assume incorrectly that you know how to protect their best interests.
Depending on the water level depth in the well, that pump may not being putting out 14 gpm for the 10 minutes of backwash and then another 5 minutes of rinse. If so then your Filox fails. And you are looking at this in the fall and don't know how things will work in a drought so...
What I would want to know, and was capable of determining when I was a local dealer is, how deep is the well, how far down to the water level?
Bob999 - I see your points. The 80 seconds I measured (before really addressing the need to adjust the pressure tank per Gary Slusser's recommendation) was from pump off to pump on. When I get back over there I'm going to properly adjust the pressure tank, redo my calculations, and see how it operates. The other thing I'm going to do is to disconnect the backwash line (there's a 1" PVC union in the line) and test the actual flowrate during a backwash cycle - then I'll know without any question what sort of rate I'm getting through there.
Gary Slusser - this house is on the waterfront of the Chesapeake Bay and is on well, but with public sewer. The owner directed the plumber to install a 6" drain line to the sewer tie-in. In this case the backwash is helping to keep the drain clean and not much else. The well is down 340 ft. and the water is sitting at 58' according to the well report and the pump installers closeout sheet. I'm pretty sure I'm getting enough flowrate... I sure hope so because there's not much more I can do - I put the correct size button in the DLFC port, ensured I had a short run to the filter, installed a 1" drain line, etc. If I were doing this again I would evaluate the wisdom of using two smaller tanks. If I can confirm the backwash rate... and I will... I might have a good solution though; one that will last a long time and solve a perplexing problem for the owner.
Dittohead's comments about frequency of backwash are consistent with what I heard pretty much across the board. The folks at Fleck (this is a Fleck 7000SXT valve) and at Matt-son insisted on 12 GPM and waiting no longer than every other day to backwash. So I have it set now for 15min backwash/5 min rinse every other day. I bumped up the button to 14GPM based on Dittohead's recommendation. I'm not too worried about lifting the bed and dumping material out during backwash because from everything I've read this media just doesn't move very much during backwash - the little bit of extra flowrate can only help.
Your note about being worried about using this much water is something very much on my mind. This past summer was absolutely brutal and though we didn't get a drought ban on water usage, if this kind of heat keeps up I'd be worried about a lot of wells drying up. The homeowners are frugal users of water, BUT they did just install an irrigation system having a drip side and a pressure side with large garden areas. The house is equipped with rainwater capture and recirculation systems, but in the summertime the wellpump really cranks when the irrigation system come on - it's all plumbed with 1" lines. You're right about water temps - this water never gets above 45 degrees. Temperature does determine the backwash flowrate, but at these temperatures 12GPM is what's recommended.
I've attached a before and after picture of the water color, shown with a few inches in a white jacuzzi - the iron filter seems to be doing its job.
You guys have been terrific help on this project and I'm very grateful!
Attachment 18344Attachment 18345
That's nice looking bath water indeed
The time from pump off to pump on is the time for the pressure tank to empty. You have computed the flow rate during backwash and confirmed that you have ~14 gpm backwash flow.
Originally Posted by traderyoda
The Filox systems usually work very well, just as yours is. The problems of the past with maganese dioxide ore based medias was usually caused by inadequtate backwashing. Congrats on the fine looking water.
That is alot of water useage. For my family, 140 gallons every two days would be at least a 50% increase in water useage. One of the other downsides to manganese dioxide iron filters.
Originally Posted by traderyoda
I guess one could add the expense of boring a dry well and return the backwash to the water table below.