Seal (Nickel Acetate or Hot Water Seals After Anodizing)
Typical pH: 5 to 6
Temperature: 90 to 212 F (32 to 100 C)
Agitation: Light to moderate
In-Tank Filtration: In a nickel acetate seal, too high of a pH can cause formation of nickel precipitates, which turn the bath milky white. By removing precipitates, bath life increases, dumping frequency decreases, and smutting diminishes. In-tank systems are also used in hot water seals to remove particulates and promote temperature uniformity.
Carbon Treatment: In-tank carbon treatment is occasionally used to assist in the removal of organic black dyes from seal tanks. The presence of the dyes is usually a result of leaching from workpieces. While in-tank carbon treatment should not be considered a panacea for this problem, some users employ it once a week or so to help reduce dye buildup. In one case, the anodizer states that overnight carbon treatment transforms the nickel seal from black to a light gray color, indicating the removal of a fair amount but not all of the dye.
Pump Material of Construction: CPVC is often specified for the low- and medium-temperature seal tanks. Polypropylene is usually preferred for seal temperatures in the range of 170 to 190 F (77 to 88 C). For seals appreciably above 190 F, two excellent choices are stainless steel or the high-temperature plastic PVDF (Kynar).
Commonly Used Filter Cartridges: Most customers start with the FK20 Poly-Spun Disposables or the PMCA Permacore Magnum Reusables in the required length. Depending on the solids generated, it may be necessary to switch to coarser cartridges (higher micron rating) to remove larger particles or finer cartridges (lower micron rating) to remove smaller particles.
Special Notes: Because this can be a very hot environment, the pump must be mounted in a well-ventilated location for maximum motor life. The pump must not be installed in front of the ventilation exhaust, as this will expose the motor to a continuous draft of hot fumes.

Silver Plating, Cyanide
Typical pH: 11.5 to 13
Temperature: Room temperature
Agitation: Mild
In-Tank Filtration: Imperative for general cleanliness and roughness prevention. In addition to continuous filtration, care should be taken to avoid the introduction of problematic small particles, including fines from damaged anode bags or grinding dust inadvertently carried in from workpieces.
Carbon Treatment: As needed
Pump Material of Construction: Polypropylene is preferred. CPVC may become brittle, then crack and split, over time in hot, highly alkaline solutions.
Commonly Used Filter Cartridges: Most customers start with the FK20 or FK10 Poly-Spun Disposables or the PMCA or PMCB Permacore Magnum Reusables in the required length. Depending on the solids generated, it may be desirable to use finer cartridges (lower micron rating) to remove smaller particles. 

Strippers, Caustic
Typical pH: 13+
Temperature: up to 225 F (105 C)
Agitation: Mild to moderate
In-Tank Filtration: Stainless-steel in-tank pumps are used to recirculate caustic chemical strippers to promote temperature uniformity and proper bath activity. Strippers that generate lots of precipitates cause filter cartridges to clog rapidly, making in-tank filtration impractical. Also, depending on the aggressiveness and temperature of the stripper, polypropylene filter cartridges may be destroyed rapidly.
Carbon Treatment: None
Pump Material of Construction: Stainless steel is the only choice.
Commonly Used Filter Cartridges: Strippers that generate low to moderate volumes of dissolved solids may be candidates for filtration. Those that generate large chunks or strips of residue tend to clog cartridges rapidly, making in-tank filtration impractical. Also, as noted above, conventional filter cartridges can degrade or deform rapidly in hot chemical strippers. The only practical alternative is a special-order Flo King stainless-steel filter cartridge, which, while very expensive, is cleanable, reusable, and lasts indefinitely. 
Special Notes: Because this can be a harsh environment, the pump must be mounted in a well-ventilated location for maximum motor life. The pump must not be installed in front of the ventilation exhaust, as this will expose the motor to a continuous draft of hot, corrosive fumes. In addition, some users brush on the pump motor a thin layer of caustic-resistant liquid maskant to prevent perforation corrosion of the motor housing. 

Tin Plating (Acid Sulfate & Methylsulfonate) & Tin-Lead
Typical pH: 1.2
Temperature: 60 to 80 F (16 to 27 C)
Agitation: Mild to moderate
In-Tank Filtration: Removes fine particulates or, in the case of aging, turbid baths, a light-colored gelatinous material. Baths are air-sensitive. Aeration converts stannous tin to stannic, leading to unwanted precipitates. In-tank pump model and body length must be properly sized to avoid aeration.
Carbon Treatment: As needed
Pump Material of Construction: CPVC often specified. Polypropylene is also excellent. Titanium shaft recommended.
Commonly Used Filter Cartridges: If the bath is generating lots of solids, most users start with the FK75 or FK50 Poly-Spun Disposables or the PMCXC or PMCXF Permacore Super Magnum Reusables in the required length. If the bath is generating finer particulates, users generally start with the FK20 Poly-Spun Disposables or the PMCA Permacore Magnum Reusables. Depending on the solids generated, it may be necessary to switch to coarser cartridges (higher micron rating) to remove larger particles or finer cartridges (lower micron rating) to remove smaller particles.
Special Notes: Because this may be a harsh environment, the pump must be mounted in a well-ventilated location for maximum motor life. The pump must not be installed in front of the ventilation exhaust, as this will expose the motor to a continuous draft of corrosive fumes.  

Tin Plating, Fluoborate
Typical pH: 1.2
Temperature: Room temperature to 100 F (38 C)
Agitation: Mild to moderate
In-Tank Filtration: Removes anode films and other debris.
Carbon Treatment: Frequent
Pump Material of Construction: CPVC often specified. Polypropylene is also excellent.
Commonly Used Filter Cartridges: Most customers start with the FK50 or FK20 Poly-Spun Disposables or the PMCA Permacore Magnum Reusables in the required length. Depending on the solids generated, it may be necessary to switch to coarser cartridges (higher micron rating) to remove larger particles or finer cartridges (lower micron rating) to remove smaller particles.

Tin Plating, Stannate
Typical pH: 12.5
Temperature: 140 to 190 F (60 to 88 C)
Agitation: Mild to moderate
In-Tank Filtration: General cleanliness.
Carbon Treatment: Rare
Pump Material of Construction: CPVC may be ok at lower temperatures, but polypropylene is preferred. CPVC may become brittle, then crack and split, over time in hot alkaline solutions.
Commonly Used Filter Cartridges: Most customers start with the FK50 or FK20 Poly-Spun Disposables or the PMCA Permacore Magnum Reusables in the required length. Depending on the solids generated, it may be necessary to switch to coarser cartridges (higher micron rating) to remove larger particles or finer cartridges (lower micron rating) to remove smaller particles.
Special Notes: Because this may be a harsh environment, the pump must be mounted in a well-ventilated location for maximum motor life. The pump must not be installed in front of the ventilation exhaust, as this will expose the motor to a continuous draft of corrosive fumes.