Mike-O-Pedia FAQs for Water Treatment Professionals
The purpose of the “Mike-O-Pedia” is to share knowledge with our peers. We will be posting on a regular basis and look forward to answering questions or discussing comments and applications with our dealer customer base.
Topic: Water Softeners
Which Salt to Do We Use?
- Sodium Chloride
- Solar Salt
- Salt pellets
- Potassium Chloride
- May be used in place of sodium chloride. If user is clinically monitoring sodium intake suggest use of reverse osmosis drinking water system.
- Chemically treated salt specifically designed to clean resin for iron removal softener.
- Softeners prevent scale.
- Softened water will dissolve calcium scale very gradually from existing plumbing.
- Caution – If your customer has experienced severe scale build up in pipes or water heating devices he/she might not see zero soft water results due to the erosion of the calcium.
- Run cold water from high flow tap to ascertain whether the water is soft -> you may experience the same with iron removal.
Removing Iron with a Water Softener
- Ferrous (Fe ++) or clear water iron can be removed by a water softener
- Compensate for hardness & manganese by using this formula:
- Compensated hardness = 2 x iron + 2 x manganese + hardness
- Gallons between regenerations = compensated hardness / capacity of softener
- If the formula yields less than 1,000 gallons between regenerations use a larger softener
- Other considerations when using a softener to remove iron:
- A higher salt dosage is required – 10-15 lbs. per cubic foot.
- Fine mesh cation resin yields better results when iron is greater than 3 ppm.
- Use of a resin cleaning system or salt is recommended.
- Do not use an upper screen. Iron will clog the slots.
- When do I NOT use a water softener for hardness and/or iron removal?
- Cloudy water iron (ferric Fe+++)
- Heavy sedimentation
- Iron bacteria
- Organic iron
- TDS greater than 450 ppm
- pH higher greater than 8.5
Water Hardness & Low pH
- Hardness greater than 10 gpg? Acid neutralizer media will not easily dissolve – place softener before neutralizer. Don’t want to do that? Feed soda ash with chemical feed pump.
- Caution – When sizing a water softener, add 4-6 additional grains of hardness to your water test to compensate for the additional hardness coming from calcium carbonate neutralizing media.
Should I use an upper screen?
- Almost always. If removing iron greater than 2 ppm remove the upper screen. Iron can accumulate on the screen and ruin the efficiency of the softener
What type of resin do I use in a softener?
- Always specify softener resin also known as cation resin must be in the sodium form (Na).
- Caution – Malfunctioning Res-Up feeders may depress pH and convert the resin from the sodium (Na) form to the Hydrogen H+ form and result in very low pH water.
How long does softener resin last?
- For residential service in chlorine & iron free water about 10-15 years.
- Where chlorine or chloramine & iron are present about 2-5 years.
Should I install a water softener to remove lead?
- A softener may be used to reduce lead however, it should always be backed up by reverse osmosis treatment at the kitchen tap.
- Lead will not affect softener operation however, Caution – contract with customer to monitor lead levels at least annually.\
Topic: Using a MAV (Motorized Alternating Valve) on a Twin, Tri or Quad Softener or Filter
Using two filter or softener tanks instead of a single tank, helps avoid failed installations. This happens when a single tank bed can no longer function because the contaminant has overwhelmed the bed and fouled the media. This can result in excessive pressure drop, and cloudy, dirty water coming out of the tap.
This problem occurs because the backwash or regenerant water is untreated raw water. The media is getting fouled at the bottom and top of the single tank. Twin tank systems solve the problem. When regeneration or backwash is called for, a portion of the water is drawn from the clean secondary tank.
This is accomplished with the use of a Clack MAV – Motorized Alternating Valve. MAV Specification
- The MAV is electronically controlled by the valve on top of each tank.
- When the primary tank is ready for regeneration or backwash the secondary “clean” tank is shuttled by the MAV and it becomes the primary tank and a portion of its water is used to regenerate/backwash the dirty or exhausted tank. It’s a shuttling method back and forth.
- Use a MAV to draw from a separate clean water source if available, then a single tank can use the clean water source for regeneration water.
- When lacking the water volume to backwash a single filter tank, two smaller tanks can be installed.
- With the correct electronic package, multiple MAV’s can operate up to four (4) tanks.
- These tanks can run in series or parallel. For example, applications which require zero (0) hardness at higher flow rates require a third or fourth tank.
- Consult us for the proper application of multiple tanks.
Topic: Understanding High Efficiency Water Softeners
How efficient are the softeners you’re selling? Why does it matter? Highly efficient softeners use less salt. Consumers will see salt savings and fewer backbreaking trips from the store to the brine tank. Environmentally there is less chloride discharge to the septic system or municipal waste system.
Typically, 1 cf of resin yields 30,000-34,000 grains if you regenerate with 15 pounds. As regulators and consumers have become more environmentally conscious demand for softeners which use less salt has increased. Highly efficient (HE) softener design is proprietary to the OEM. Through the use of specially designed tanks, distributors and valves, these softeners get 4,300 grains of capacity with just 1 pound of salt.
The easiest way to explain this to think about the way a sponge is used. A sponge effectively cleans a surface when it is damp. If you use a sponge which is soaked with water the cleaning process is messy. The excess water will come out of the sponge onto the surface. The result would be a very wet surface which is only partially clean.
You don’t need 15 pounds of salt to effectively regenerate the HE softener. There are diminishing returns. Using a 1 cubic foot softener here are the numbers:
- 5 pounds yields 4,311 grains per pound or 19,000 grains
- 6 pounds yields 3,800 grains per pound or 23,000 grains
- 15 pounds yields 2,255 grains per pound or 33,000 grains
As you see, you get more total grains when using 15 pounds. The problem with that 15 pounds is that you go through a bag of salt more quickly than if you use 4.5 pounds. A 50-pound bag of salt yields 3.3 regenerations when using 15 pounds per regeneration. Using that same 50-pound bag at 4.5-pound regenerations the yield is 11 regenerations.
⚠️Using less than 4.5 pounds of salt is not recommended. At lower rates the resin beads will not be sufficiently regenerated and shorter run lengths will result.
Additional savings with high efficient softeners include:
- Water usage is greatly reduced
- Electrical savings – well water pump
- Impact on septic system is not as great
- Chloride discharge to municipal waste treatment plants is reduced.
These systems have been designed and manufactured by OEM’s who sell entire systems and not just the components. There are OEM’s who sell HE softeners to independent dealers.
Can a High Efficiency softener be used if there is iron and manganese in the water?
In the northeastern U.S. we use water softeners to remove these contaminants. The species of iron and manganese are easily removed because there is low TDS and not much competition of other cations. (It’s mostly a dissolved, low pH water.) These softeners are fondly called “salt hogs” because you need to regenerate with a lot of salt to drive the iron and manganese off of the resin.
A HE softener can be tweaked to increase the salt dosage to compensate for the iron and manganese. Rather than using the full 15 pounds of salt you can cut back to 10 pounds of salt.
Topic: Distributions Systems – Tank Internals
Riser Tube, Standpipe, Distributor Tube
- A distributor tube consists of a plastic or stainless-steel tube attached to a distributor, also called a diffusor, collector or basket.
- Its purpose is to produce even flow through an ion exchange or filter media bed. It also functions as a retainer of the media in the tank.
- The screen size of the basket should be appropriate for the media being used.
- The tube length is cut to match the tank size and valve.
Question: When should a gravel sub-fill be used in a mineral tank?
When to Use Gravel Sub-Fill
|Carbon Filters - Backwashable Type||Yes||If recycling carbon, separation of gravel from carbon is required.|
|Carbon Filters VOC Removal||No||Backwashing a carbon filter used for VOC removal will upset the mass transfer zone and may result in leakage of the contaminants.|
|Acid Neutralizers||Yes||Upflow & Downflow systems|
|Softening - Upflow||No||N/A|
|Softening - Downflow||Yes||Creates a better flow pattern.|
Hub & Lateral Tank Internals
- For systems incorporating tank sizes above 14”, a hub and lateral design distribution system is used.
- Hub and laterals are available in PVC, ABS, poly pro and Stainless Steel.
- Valve size dictates the size of the distributor which in turn dictates the size of the hub.
- Laterals for filters and ion exchange differ in slot size.
- Filter media type and backwash rates vary and generally require a slightly larger slot opening than ion exchange resin.
- Ion exchange laterals usually have .010” slots whereas filter laterals slots are .020”.
- Filter media type and backwash rates vary and generally require a slightly larger slot opening than ion exchange resin.
- Performance of large commercial and industrial systems is impacted by distribution design.
Urbans Aqua offers standard and custom distribution systems.
Topic: Activated Carbon
GAC Specifications – What do they measure?
How closely in size is the contaminant to a molecule of iodine? The higher the iodine number the better the removal of molecules which closely resemble iodine. Iodine is a small molecule therefore it measures ability to adsorb lower molecular weight smaller substances.
Molasses number Is a measurement of the degree of decolorization of a standard molasses solution. It is a relative guideline for measuring the capacity of the carbon to remove color molecules.
Demonstrates the carbons ability to withstand degradation during handling – before and after it is placed into service. Lower abrasion numbers result in more dust and fines.
Density, Backwashed & Drained (BWD)
This is the number of pounds required to fill a cubic foot of volume capacity. Caution– The density of activated carbon types varies.
TCN – Trace Capacity Number
The Trace Capacity Number measures the number of high energy pores in an activated carbon product. These high energy pores are required to remove difficult to adsorb contaminants, such as MTBE. The theory behind the test is similar to the Iodine number, where the iodine number reports the mg Iodine per gram of carbon in a standard iodine solution. Since iodine is so strongly adsorbed, it is essentially fills all of the adsorption pores (high energy and low energy). The TCN number uses a more difficult to adsorb species and reports the mg loaded per gram of carbon. A higher TCN number on a carbon would indicate a higher number of high energy pores, which would suggest better loading in an application with difficult to remove contaminants.
The ash content of a carbon can be defined as the noncombustible mineral matter that is contained in activated carbon. It is the residue that remains after the combustion of a carbonaceous material and is normally defined on a weight basis. The ash content is dictated by the raw material used to manufacture an activated carbon product and is why a high purity raw material is necessary to produce a high purity activated carbon product. There are also additional post-processing steps, such as acid washing, to reduce the amount of ash content in an activated carbon product.
Water Soluble Ash
Ash measures the level of purity. It is the inorganic residue left after the heating process. It consists of silica, calcium, alumina, iron, magnesium with a potential for arsenic. Carbon may be acid washed or water rinsed to reduce ash content. Water extractable ash has the highest impact on the product quality as it affects the effluent.
Can Activated Carbon be regenerated?
Activated carbon cannot be regenerated like ion exchange resin. Activated carbon can be reactivated by carbon manufacturers. The reactivation process is similar to the original activation process. The resulting product is distributed for waste water applications. Municipalities contract to reactivate segregated lots for re-use.
It is possible to reactivate activated carbon with steam. Beverage manufacturers have large carbon filters which have steam injection. The heat from the steam will push off the more weakly held contaminants freeing up pores for continued use. The steam also sanitizes the carbon bed. Steam reactivation will restore the life of the carbon bed but eventually the cost outweighs the benefit and a new carbon bed must be installed.
Which type of carbon do I use?
Hydrogen Sulfide (H2SO4)
- Use Catalytic Carbon only in a single tank with peroxide – download article here Applying Peroxide
- In presence of sulfur reducing bacteria (black slime) treat with chlorine and KDF cubes.
- Centaur Specifications – Coal Base Activated Carbon Centaur_Catalytic_Adsorptive_Carbon_Brochure
- Jacobi CXMCA Specifications – Jacobi CX-MCA
- KDF Cubes Information https://www.urbansaqua.com/products/filter-media/kdf-cubes/
- Use any carbon for chlorine removal. It is a chemical reaction is on the surface of the carbon similar to ion exchange.
- Backwashing extends the life by removing sediment from the carbon bed.
- Rebed or change out the activated carbon when black particles or gray water is seen in standing water – such as toilet bowls; or when there is increased pressure drop across the carbon bed.
- Except to polish after primary treatment activated carbon is not recommended for tannin removal.
VOC (Volatile Organic Contaminants)
- Caution – there are too many variables contact the Urbans Aqua for help.
PFAS POS POA PFOA
- Only coal based carbon should be used. Calgon F-400 is a good choice.
- Dual tank operation – worker / guard with sample port between and after.
- Strongly recommend use of a totalizing meter after guard tank.
Taste and Odor
- Any carbon will work.
Pre-treatment to RO
- Coconut base carbon is physically harder and produces very little fines.
High Purity Applications
- Acid Washed Carbon removes dissolved, naturally occurring metals.
How to remove PFOA & PFOS from drinking water using Calgon Carbon.
- Choose the right carbon – Calgon Carbon has been working with PFOA for 15 years and their studies and experience shows that coal base carbon is the way to go.
- F-400 works very well and isn’t as expensive as F-600AR+. Coal Base Activated Carbon Filtrasorb 400
- F-600AR+ is a great choice though on the pricey side. It must be used in some states including New York. Calgon FILTRASORB 600AR+
- If you choose another brand of coal base carbon be sure it has been tested and will not throw off arsenic.
- The empty bed contact time (EBCT) for PFOA is 10+ minutes and can be as long as 20 minutes.
- Use multiple carbon tanks (lead/lag) with a sample port between them.
- Backwash with treated water if possible.
- After installation, let the system run for a couple of days before drawing a sample for testing.
- EPA limit for PFOA & PFOS is 70 ppt – that’s parts per trillion. EPA PFOS PFOA Health Advisory
- The EPA is addressing PFAS EPA PFAS Action Fact Sheet 021319-final-508compliant
- The limit varies state by state so make sure you check before installing. It’s never higher than 70 ppt. PFAS Contamination by State
- Some states have placed restrictions on arsenic (naturally occurring) which may come off the carbon.
- Waste & Handling
- Carbon used for PFAS removal should be incinerated and not land filled.
- The generator (homeowner) is responsible for the disposal of the spent carbon. However, you should consider talking with your Calgon Carbon supplier who can assist in obtaining a Carbon Acceptance Number (CAN). There is cost associated with the testing and application but it is a green and sustainable means of handling the spent carbon. The spent carbon is reactivated and reused in applications where virgin carbon isn’t required.
- There are no special handling requirements when removing the carbon used to remove PFOA and PFOS. Handle as you would any other activated carbon rebed. Gloves, dust mask and safety glasses.
- Calgon Carbon Literature: PFC-Webinar-Presentation-1-30-17
What is Enhanced Coconut Carbon?
- According to Calgon Carbon enhanced coconut is basically a standard coconut product that undergoes additional processing (chemical fluxing agents and thermal conditions) to transform a coconut’s pore structure to be more like a reagglomerated bituminous coal-based product. Coconut based activated carbons traditionally have a very tight pore structure (microporous) while reagglomerated bituminous coal based products have a broad range of pore structures (micro, meso, and macroporous).
Chloramine Removal with Activated Carbon
To meet tougher THM (trihalomethane) standards municipalities are moving to chloramine disinfection.
- Chlorine creates higher levels of trihalomethanes.
- Chloramine is more stable and a much weaker oxidant so resultant THM levels are lower.
- Helps protect the consumer by reducing the cancer-causing disinfection byproducts.
Drill down and it’s a little more complicated:
- In potable water, chloramine can exist as monochloramine, dichloramine and trichloramine.
- Because municipal water is delivered with a pH between 6 and 9, monochloramine is the predominant species used for disinfecting.
- Monochloramine is also the most difficult type of chloramine to remove using carbon.
Example 1: Homeowner who wants to remove all traces of chloramine (or chlorine) and the THMs from their city water. No problem? Think again.
- In a side by side comparison of standard and catalytic carbon the removal efficiency is initially the same.
- On standard carbon a slower removal rate occurs as the catalytic sites are used up (and supplanted by carbon oxides).
Because the chloramine reaction is catalytic in nature, activated carbons with enhanced catalytic activity are more efficient, last longer and enable you to use smaller equipment.
- Before prescribing the correct solution, ask the question – are we removing chlorine or chloramine?
- Chlorine -> Activated Carbon – 12×40, coal, coconut (piece of cake).
- Chloramine -> Catalytic Carbon such as Centaur® -> 12×40 in a smaller tank
Example 2: The pH of the water we were treating was not between 6 and 9. It was around 4. Even though the water was being treated with carbon there was residual chlorine which set off alarms. If the pH was high, no problem. Of course we contacted the experts at Calgon for help. Their first question – Were we dealing with chlorine or chloramine?
Long story short – The municipal water being disinfected with chloramine. At the lower pH the species is trichloramine, or nitrogen trichloride.
With activated carbon the catalytic reaction with chloramine is opposite of chlorine.
- Chlorine destruction is enhanced at low pH.
- Chloramine destruction is enhanced at high pH.
The trichloramine was sneaking through the carbon because the pH was low. The solution – either raise the pH or use a catalytically enhanced coal base carbon such as Centaur® to resolve.
Topic: Arsenic Removal
Arsenic is a grey, semi-metal element. Arsenic enters ground water from both natural sources and human activity. Contamination can sometimes be traced to deep-water brines produced from gas and oil well drilling. It is also be found in wood preservatives and may be a byproduct of herbicide production.
Arsenic has a primary drinking standard because it is known to have health effects when present in drinking water. Skin lesions, circulatory problems and nervous disorders can occur. Prolonged exposure may result in skin, bladder, lung and prostate cancer. For this reason, the EPA has set the MCL to 0.01 mg/L (micrograms per liter). Arsenic removal from wells
Arsenic Reduction/Removal from Water
Arsenic is one of the hardest ions to remove from water. It usually occurs in water as either arsenate (AsV) or arsenite (AsIII). Test results report the total arsenic concentration including arsenic as arsenate and arsenic as arsenite. Aresenite is a greater health concern and more difficult to remove. For this reason, most treatment solutions start by adding an oxidant to the water to convert all arsenic to the arsenate form. Oxidation can be accomplished through the addition of chlorine, ozone or greensand. Note: Chloraminated water utilizing only monochloramine (NH2Cl) will not completely oxidize AsIII to AsV).
Heating or boiling water will not remove arsenic from water, it may increase the concentration as the water is evaporated off.
To determine the best removal treatment the water must first be tested by a certified lab.
Removal methods include Activated Alumina, Manganese Greensand Filtration, Distillation, and Reverse Osmosis. Urbans Aqua offers specialty products – Purolite’s FerrIX™ A33E and Graver’s Metsorb®. All products used for arsenic removal should be NSF or WQA Gold Seal Certified.
Before embarking on a treatment regiment, a full water analysis is necessary. Since Arsenic is anionic, you must test for competing anions. Both Purolite and Graver have a water profile work sheet that must be filled out, so they can better estimate bed life. Contact Urbans Aqua for equipment system design.
Arsenic Removal Products – Pros & Cons
- Easy maintenance
- Potential for non-hazardous disposal as solid waste
- Highly selective for AsV; AsIII must be oxidized
- pH < 6.5 or lower if silica is present
- Reduces to < 2 ppb
- Only practical for small quantities of water
Ion Exchange Anion SBA I & II
- Effective for AsV
- Optimum pH >7
- AsIII must be oxidized and removed prior to resin bed.
- Nitrate, fluoride, selenium & sulfate will compete with AsV for exchange sites resulting in earlier exhaustion.
- Effective for AsV
- AsIII must be oxidized and removed prior to greensand filter.
- Iron must be present in raw water equal to or greater than the arsenic.
- Effective for AsV
- AsIII must be oxidized and removed prior to RO.
- Care must be taken to prevent damage to membrane.
- Selective removal of arsenic.
- pH for treatment 7
- Operates similarly to ion exchange resin.
- EBCT 2.5-5 Minutes (typically 3 minutes).
- No Regeneration
- Low pressure differential
- Potential for nitrate dumping.
- Offsite regeneration available for large installations.
- Removes AsV & AsIII.
- EBCT 1.5-3 Minutes.
- Also removes lead, cadmium, copper, zinc, chromium+6 & selenium.
- Potential for non-hazardous deposal as solid waste.
- No regeneration
- Potential for high pressure differential
Common Residential Installation Problems & Challenges
Not enough water to backwash filters.
- Carbon filter backwash rate = 8-10 gallons per square foot.
- Greensandplus/Pyrolox Advantage backwash rate = 12-15 gallons per square foot.
- Birm backwash rate = 10-12 gallons per square foot
- Backwash Rates
- How old is the well pump? Should it be replaced?
- Is the well pump a jet pump? If so, consider replacing. Jet pumps may not be powerful enough.
- Test the circuit with a Voltmeter
- Be sure you are plugging the system into 120V not a 220V outlet.
- Does the electrical system look like a spider-web? Is lamp wire coming into the outlet box?
- Suggest the owner invest in an upgrade before adding equipment.
- Is the system wired into the light switch? Turn the light on it works, off – it doesn’t.
- Kinetico Systems don’t use electric – above does not apply.
- Test the circuit with a Voltmeter
Inadequate space for the installation
- Crawl space installations – Is the system properly designed? Capacity may be compromised because the equipment is smaller than normal.
- UV light – What is the overall length of the system? Is there enough space for bulb replacement? Bulb replacement requires space double the bulb length.
Drain water discharge
- Do not discharge to the well pit.
- Be sure to use an air gap when direct connecting to a septic or drain.
- An illegal drain is a direct connection with no air gap. Air gap should be 1-1/2 times the diameter of the drainpipe. Check local codes.
- Drain is too slow – can’t accept the volume of water from the backwash.
- Don’t take their word for it – flush some toilets, run the spigots.
- Will the water backup in the basement?
- Will the septic system handle it?
- Take a walk outside to see if there are ugly gray spots or a bright green swamp over the septic drain field?
- Do the state/local authorities allow installation of water softeners?
- Delaware requires a waiver; check with your local government before installing.
- Always use a high efficiency demand softener system. No time clock regenerations.
- Don’t take their word for it – flush some toilets, run the spigots.
What is the water temperature?
- Temperature affects efficiency of Reverse Osmosis.
- Colder water is denser so there is more lift. More backwash water lift than warm water system.
- Cable company, telephone company, security company equipment is grounded to the copper pipe sending milliamps in the plumbing resulting in pinholes and leaks.
- Ground the plumbing to an outdoor ground with a proper pole, hammered into the ground.
Common Commercial/Industrial Installation Problems & Challenges
- See all of the above.
Will the system fit?
- How wide are the mineral and brine tanks? How wide is the doorway, elevator, etc.?
- Is the ceiling high enough to accommodate the system?
Are the drains open and available to use?
Is there enough water and water pressure to operate properly?
If an electrician is required – who will provide?
Is current electrical up to code?
Do you know who are you working with? Is everyone on the customer’s team aware of the scope of work?
- Plant manager, boiler operator, purchasing agent, etc.
How will the system be transported?
- Is it going up a stairway to a mezzanine? How will it be moved, who will move it – customer or vendor (you)?
- Forklift – for delivery purposes and/or installation/rebed purposes.
- Is a forklift available for your use?
- Who is authorized to drive it?
- Will you have to wait, or will it be ready for use?
- Do you have to rent a forklift?
What are the safety regulations?
- Will there be a safety meeting at the start of the job? How long will it be?
- Clothing – long sleeves, no shorts, steel toed shoes, etc.
- Facial hair allowed?
- Safety meeting prior to job start.
- Lock Out, Tag Out
- Confined Space
Is the facility union or non-union?
Is there adequate parking? Sites may have restricted areas.
Topic: Resins – Mixing Cation and Anion Resin in One Tank – (NOT MIXED BED RESIN)
The resins we are discussing here are as follows:
- Anion Resin – Chloride form specialty resin used to remove sulfates, nitrates, tannins, alkalinity
- Cation Resin – sodium form softening resin used to remove hardness – calcium, magnesium
When these resins are in separate tanks the cation always goes ahead of the anion tank. As a result, the hardness minerals are removed before the water goes through the anion resin.
- Both are regenerated with sodium chloride – salt. Use of this common regenerant creates the opportunity to combine the resins in one tank. Anion resin is lighter and rests at the top of the resin bed; cation is beneath it.
- Sodium (Na) exchanges with hardness minerals
- Chloride (Cl) exchanges with anions – sulfate, nitrate, etc.
A potential problem may occur as a result if the water hardness is above 6-8 grains hardness.
- During regeneration the ion “exchange” happens.
- The minerals (calcium) are being washed away and the salts (contaminant varies depending on desired outcome) are also being washed away.
- These “waste” products foul the anion resin and combine to create calcium carbonate, a cement like substance which blocks the drain.
How to avoid the problem.
- Use separate tanks for cation and anion.
- Add phosphoric acid to the brine. By acidifying the calcium remains in
- Pro Res Care Easy Feeder (Manufactured by Pro Products may purchase direct or from local supplier)
- Res Up Feeder (Manufactured by Clack – purchase only from local supplier)
How to repair.
- Clean the drain line by breaking up the calcification.
- Portions of seal pack and injectors may need to be replaced. Best to rebuild the valve before putting back in