Looking for inputs on water treatment recommendation

[SShaw]

I’d like to get some independent input on a water treatment recommendation.

I have a shallow well with pure water and low pH. The water is corrosive to copper piping. I recently installed a geothermal heat pump with a desuperheater to make hot water. The desuperheater has a copper heat exchanger. The heat pump manufacturer recommended I install water treatment to avoid corrosion and scale problems. I am working with a local water company on this. The water analysis is as follows:

pH: 6.5
Hardness: 1.2 gpg
Iron: 0.03 ppm
Manganese: 0.019 ppm
Tannin: 0.1 ppm
TDS: 66 ppm
Alkalinity: 50
Solids: Slight. Low range gneiss and small % quartz undissolved rock solids. Marginal issue.
Odor: Faint. Must. Common for this chemistry. Marginal issue.

The water company recommended a 2.5 cubic ft 13x54 backwashing acid neutralizer followed by a 20” Big Blue cartridge filter with “Siliphos” polyphosphate crystals. For the neutralizer, they recommended a blend of 80% calcite and 20% “Filter Ag+” silicon dioxide media. The filter is intended to raise the pH and trap suspended particles. The polyphosphate is intended to prevent corrosion and sequester the additional hardness added by the neutralizer to prevent scaling.

They recommended a 12-day electromechanical time-clock Fleck 2510 valve for backwashing every 12-days. The water company specs indicates a 7 GPM backwash with a 140 gallon backwash cycle.

The house is a weekend home that’s usually only occupied Friday night through Sunday night. I like to turn off the main water supply when when I leave.

The filtering recommendations make sense to me. I do have a couple concerns and questions though:

1. A valve that backwashes every 12 days doesn’t seem to mesh well with the weekly use schedule for the house, and seems more frequent than necessary. In response to this information, the company recommended a 7-day timer, which would basically backwash 140 gallons for every two days of use, which seems like a waste of water. What would be the recommended strategy for a scenario like mine? Is backwashing every 7-days really required, or should it be something like every six weeks, which would equate to 12 days of water use? I see some filters have a metered option. Would backwashing based on quantity of water used be a better approach?

2. Is 2510 electromechanical valve a good choice, or is there a better choice? At a minimum, I think I would like to have the 2510 SXT, which appears to have the flexibility of programming 0-99 days for the timed backwash.

3. The pressure tank holds about 5 gallons and the well pump fills the tank at about 9 GPM. The supply pipe from the well is 1” ID HDPE to the pressure tank. The pipe out of the tank to the rest of the house is 3/4” ID PEX. Would it be better to connect the filters to the pressure tank using 1” pipe, or is the 3/4” OK?

I appreciate inputs on the best approach for my situation.

 

[ditttohead]

I’d like to get some independent input on a water treatment recommendation.

I have a shallow well with pure water and low pH. The water is corrosive to copper piping. I recently installed a geothermal heat pump with a desuperheater to make hot water. The desuperheater has a copper heat exchanger. The heat pump manufacturer recommended I install water treatment to avoid corrosion and scale problems. I am working with a local water company on this. The water analysis is as follows:

pH: 6.5
Hardness: 1.2 gpg
Iron: 0.03 ppm
Manganese: 0.019 ppm
Tannin: 0.1 ppm
TDS: 66 ppm
Alkalinity: 50
Solids: Slight. Low range gneiss and small % quartz undissolved rock solids. Marginal issue.
Odor: Faint. Must. Common for this chemistry. Marginal issue.

The water company recommended a 2.5 cubic ft 13x54 backwashing acid neutralizer followed by a 20” Big Blue cartridge filter with “Siliphos” polyphosphate crystals. For the neutralizer, they recommended a blend of 80% calcite and 20% “Filter Ag+” silicon dioxide media. The filter is intended to raise the pH and trap suspended particles. The polyphosphate is intended to prevent corrosion and sequester the additional hardness added by the neutralizer to prevent scaling.

They recommended a 12-day electromechanical time-clock Fleck 2510 valve for backwashing every 12-days. The water company specs indicates a 7 GPM backwash with a 140 gallon backwash cycle.

The house is a weekend home that’s usually only occupied Friday night through Sunday night. I like to turn off the main water supply when when I leave.

The filtering recommendations make sense to me. I do have a couple concerns and questions though:

1. A valve that backwashes every 12 days doesn’t seem to mesh well with the weekly use schedule for the house, and seems more frequent than necessary. In response to this information, the company recommended a 7-day timer, which would basically backwash 140 gallons for every two days of use, which seems like a waste of water. What would be the recommended strategy for a scenario like mine? Is backwashing every 7-days really required, or should it be something like every six weeks, which would equate to 12 days of water use? I see some filters have a metered option. Would backwashing based on quantity of water used be a better approach? Calcite should be backwashed weekly regardless as it tends to cement up.

2. Is 2510 electromechanical valve a good choice, or is there a better choice? At a minimum, I think I would like to have the 2510 SXT, which appears to have the flexibility of programming 0-99 days for the timed backwash. SXT

3. The pressure tank holds about 5 gallons and the well pump fills the tank at about 9 GPM. The supply pipe from the well is 1” ID HDPE to the pressure tank. The pipe out of the tank to the rest of the house is 3/4” ID PEX. Would it be better to connect the filters to the pressure tank using 1” pipe, or is the 3/4” OK? Connect it to the 3/4" pipe, this is fine.

I appreciate inputs on the best approach for my situation.

The recommended equipment may not seem conventional but it should work well for your application.

1. A valve that backwashes every 12 days doesn’t seem to mesh well with the weekly use schedule for the house, and seems more frequent than necessary. In response to this information, the company recommended a 7-day timer, which would basically backwash 140 gallons for every two days of use, which seems like a waste of water. What would be the recommended strategy for a scenario like mine? Is backwashing every 7-days really required, or should it be something like every six weeks, which would equate to 12 days of water use? I see some filters have a metered option. Would backwashing based on quantity of water used be a better approach? Calcite should be backwashed weekly regardless as it tends to cement up.

2. Is 2510 electromechanical valve a good choice, or is there a better choice? At a minimum, I think I would like to have the 2510 SXT, which appears to have the flexibility of programming 0-99 days for the timed backwash. SXT

3. The pressure tank holds about 5 gallons and the well pump fills the tank at about 9 GPM. The supply pipe from the well is 1” ID HDPE to the pressure tank. The pipe out of the tank to the rest of the house is 3/4” ID PEX. Would it be better to connect the filters to the pressure tank using 1” pipe, or is the 3/4” OK? Connect it to the 3/4" pipe, this is fine.​

 

[Sponsor]

 

[Reach4]

The water company recommended a 2.5 cubic ft 13x54 backwashing acid neutralizer followed by a 20” Big Blue cartridge filter with “Siliphos” polyphosphate crystals.

I think a neutralizer could be used on your 6.5 pH water, OR polyphosphate could be used. I don't know that you would need both. I am not a pro.

 

[SShaw]

Thanks for the input dittohead and reach4!

I've read conflicting things about calcite hardening, so I wasn't sure. If it's backwashed weekly but the water was only used for two days, can the backwash duration be reduced somewhat from the 20 min (140 gal) recommendation?

I haven't read anything yet that said Siliphos would raise pH. The water treatment guy did suggest soda ash injection as a possible option before he did the water analysis though.

 

[ditttohead]

Shorter backwashes tend to be fine for your application.

Calcite will raise the pH and hardness but will also likely cause some scale and maybe some annoying spotting/hardness... silophos will likely lessen the problem. If the hardness were higher then a softener would be recommended but since your levels are so low to begin with this is a decent idea. Soda ash injection with polyphosphate would also be a good solution.

 

[SShaw]

Thanks guys. The water treatment company is going to install the described system with a 2510 SXT valve. It's clear they would prefer sticking with the old analog style, though, saying it's more reliable and easier to service.

 

[ditttohead]

Old school guys, that is fine. The electronic controllers are extremely reliable. In the early 80's they were problematic but not nowadays. I used to prefer the mechanical timers too, but I got over it about 20 years ago. These are the same guys who think carburetors are better than fuel injection. And lets not start a war on why they are or aren't...

 

[SShaw]

Definitely old school!

 

[Reach4]

the company recommended a 7-day timer, which would basically backwash 140 gallons for every two days of use, which seems like a waste of water.

You are presuming that each backwash would take 140 gallons? That sounds high. You would be using a 10 inch or 12 inch tank, right?

 

[Bannerman]

Reach, SShaw said in his opening post:

The water company recommended a 2.5 cubic ft 13x54 backwashing acid neutralizer ...

 

[ditttohead]

You are presuming that each backwash would take 140 gallons? That sounds high. You would be using a 10 inch or 12 inch tank, right?

I missed this one... how do you regenerate every other day with a 7 day timer?

 

[Reach4]

I missed this one... how do you regenerate every other day with a 7 day timer?

I think he is saying that he expects to be there only 2 days per week. So even tho the regen is every 7 days, the water is only being utilized for two days of that week.

7 gpm on a 13 inch tank seems a little light. He is thinking a 20 minute backwash to use 140 gallons each time, and that seems long.

 

[SShaw]

I think he is saying that he expects to be there only 2 days per week. So even tho the regen is every 7 days, the water is only being utilized for two days of that week.

7 gpm on a 13 inch tank seems a little light. He is thinking a 20 minute backwash to use 140 gallons each time, and that seems long.

Yes, that's what I was saying.

The spec sheet for the filter says:
Service flow rate continuous: 8 gpm
Service flow rate intermittent: 10 gpm
Required for backwash: 7 gpm
Typical gallons used: 140 gal

I inferred 20 minutes backwash time from the above (140 / 7 = 20).