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Pentair CS400™ Semi-Automatic Backwash Controller for 5-Tank Systems

by Pentair
$8,950.00

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✓ Authorized Dealer
✓ Free Shipping
✓ Manufacturer Warranty
✓ Expert Support

The Pentair CS400™ Semi-Automatic Backwash Controller for 5-Tank Systems simplifies the backwash cycle of Stark™ and THS Series® commercial filtration systems equipped with diaphragm-valve face piping kits. With Acu-Trol® Intelligence, this programmable controller can backwash up to six filters in sequence via an integral multi-port pressure distribution valve — saving water, energy, and operator time on every backwash cycle.

A backwash can be initiated three ways: single-touch semi-automatic button, external signal from a master controller such as the Acu-Trol AK600, or an optional differential pressure switch for automatic backwash functionality. Features user-configurable settings, automatic calculated backwash cycle time, stored backwash data and history, alarms, heater cool-down (Fireman's delay), and valve control for pump and heater protection. Compatible with Acu-Trol AcuPort™ for network connectivity.

Key Features

Three Backwash Initiation Modes

Single-touch semi-automatic, external signal from AK600 master controller, or optional differential pressure switch for basic automatic operation.

Up to 6 Filters in Sequence

Integral multi-port pressure distribution valve actuates diaphragm-style backwash valves using city water pressure or compressed air — up to 6 filters per cycle.

"Advance" Feature — Water and Energy Savings

Skips unnecessary backwash cycles — one of the most eco-friendly commercial backwash controllers on the market.

Acu-Trol® Intelligence

Automatic calculated backwash cycle time, stored backwash data and history, user-configurable settings, and alarms.

Heater Cool-Down (Fireman's Delay)

Valve control ensures pump and heater protection prior to backwash cycle start — standard safety sequence.

Network Connectivity

Connect to networks via optional Acu-Trol AcuPort™. Compatible with Acu-Trol AK600 multi-body water chemistry and pump room controller.

LCD Display

Clear LCD interface for programming, monitoring, and alarm status.

Compatible with Stark™ and THS® Filters

Designed for Stark™ and THS Series® filtration systems with diaphragm-style backwash valves.

Who It's For

  • Commercial aquatic facilities operating Stark™ or THS Series® filter systems with diaphragm-valve piping kits
  • Filter rooms with up to 6 filters requiring automated or semi-automated backwash sequencing
  • Operations integrating with Acu-Trol AK600 master controllers or AcuPort™ network systems
  • Facilities seeking to reduce backwash water consumption and energy costs through intelligent cycle management

Specifications

Controller

Max Filters Supported Up to 6 in sequence
Compatible Filters Stark™ and THS Series® with diaphragm-valve face piping kits
Backwash Initiation Semi-auto (button), external signal (AK600), differential pressure switch (optional)
Valve Actuation City water pressure or compressed air
Display LCD
Color Blue

Physical

Product Weight 25 lb
Shipping Dimensions 18 × 20 × 24 in

Warranty

Warranty 60 Days

Warranty

The Pentair CS400 Backwash Controller comes with a 60-day manufacturer warranty. Clearflow Pool Supply is an authorized Pentair dealer and will assist with any warranty service needed.

Frequently Asked Questions

What is the difference between semi-automatic and automatic backwash?

The CS400 is a semi-automatic controller — a backwash cycle requires a human action to initiate (pressing the button or receiving an external signal). With an optional differential pressure switch added, the controller can trigger automatically when filter pressure rises to a set threshold, providing basic automatic backwash functionality without full automation equipment.

Is this compatible with all commercial filter systems?

No. The CS400 is specifically designed for Pentair Stark™ and THS Series® filtration systems equipped with diaphragm-valve face piping kits. It is not compatible with other filter types or brands. Confirm your filter system's piping kit configuration before ordering.

Description
✓ Authorized Dealer ✓ Free Shipping ✓ Manufacturer Warranty ✓ Expert Support

The Pentair CS400™ Semi-Automatic Backwash Controller for 5-Tank Systems simplifies the backwash cycle of Stark™ and THS Series® commercial filtration systems equipped with diaphragm-valve face piping kits. With Acu-Trol® Intelligence, this programmable controller can backwash up to six filters in sequence via an integral multi-port pressure distribution valve — saving water, energy, and operator time on every backwash cycle.

A backwash can be initiated three ways: single-touch semi-automatic button, external signal from a master controller such as the Acu-Trol AK600, or an optional differential pressure switch for automatic backwash functionality. Features user-configurable settings, automatic calculated backwash cycle time, stored backwash data and history, alarms, heater cool-down (Fireman's delay), and valve control for pump and heater protection. Compatible with Acu-Trol AcuPort™ for network connectivity.

Key Features

Three Backwash Initiation Modes

Single-touch semi-automatic, external signal from AK600 master controller, or optional differential pressure switch for basic automatic operation.

Up to 6 Filters in Sequence

Integral multi-port pressure distribution valve actuates diaphragm-style backwash valves using city water pressure or compressed air — up to 6 filters per cycle.

"Advance" Feature — Water and Energy Savings

Skips unnecessary backwash cycles — one of the most eco-friendly commercial backwash controllers on the market.

Acu-Trol® Intelligence

Automatic calculated backwash cycle time, stored backwash data and history, user-configurable settings, and alarms.

Heater Cool-Down (Fireman's Delay)

Valve control ensures pump and heater protection prior to backwash cycle start — standard safety sequence.

Network Connectivity

Connect to networks via optional Acu-Trol AcuPort™. Compatible with Acu-Trol AK600 multi-body water chemistry and pump room controller.

LCD Display

Clear LCD interface for programming, monitoring, and alarm status.

Compatible with Stark™ and THS® Filters

Designed for Stark™ and THS Series® filtration systems with diaphragm-style backwash valves.

Who It's For

  • Commercial aquatic facilities operating Stark™ or THS Series® filter systems with diaphragm-valve piping kits
  • Filter rooms with up to 6 filters requiring automated or semi-automated backwash sequencing
  • Operations integrating with Acu-Trol AK600 master controllers or AcuPort™ network systems
  • Facilities seeking to reduce backwash water consumption and energy costs through intelligent cycle management

Specifications

Controller

Max Filters Supported Up to 6 in sequence
Compatible Filters Stark™ and THS Series® with diaphragm-valve face piping kits
Backwash Initiation Semi-auto (button), external signal (AK600), differential pressure switch (optional)
Valve Actuation City water pressure or compressed air
Display LCD
Color Blue

Physical

Product Weight 25 lb
Shipping Dimensions 18 × 20 × 24 in

Warranty

Warranty 60 Days

Warranty

The Pentair CS400 Backwash Controller comes with a 60-day manufacturer warranty. Clearflow Pool Supply is an authorized Pentair dealer and will assist with any warranty service needed.

Frequently Asked Questions

What is the difference between semi-automatic and automatic backwash?

The CS400 is a semi-automatic controller — a backwash cycle requires a human action to initiate (pressing the button or receiving an external signal). With an optional differential pressure switch added, the controller can trigger automatically when filter pressure rises to a set threshold, providing basic automatic backwash functionality without full automation equipment.

Is this compatible with all commercial filter systems?

No. The CS400 is specifically designed for Pentair Stark™ and THS Series® filtration systems equipped with diaphragm-valve face piping kits. It is not compatible with other filter types or brands. Confirm your filter system's piping kit configuration before ordering.

Shipping

Shipping Policy

At ClearFlow Pool Supply, we keep things simple.

👉 Free shipping on all orders within the United States.
No hidden fees. No surprises.


Order Confirmation

As soon as you place your order, you’ll receive an order confirmation email.

This means:

  • we’ve received your order
  • your payment method has been pre-authorized

Once your order is in our system, we verify:

  • product availability
  • inventory status with our suppliers

If an item is unavailable or backordered, we will:

  • void the pre-authorization
  • contact you promptly to discuss alternatives

If your item is in stock and ready to ship (typically within 3–5 business days), your order will be processed and prepared for shipment.


Order Shipment

Orders that are in stock will typically ship within 3 business days.

You will receive a shipping confirmation email with tracking details within 24 hours of your order leaving the warehouse.

If you do not receive tracking information within 4 business days, please contact us at:

👉 support@clearflowpoolsupply.com 


Shipping Scope

We currently ship to customers within the United States.

Due to the size and nature of many pool equipment products, some orders may ship via freight carriers. Delivery times may vary depending on location and product availability.


International Orders

At this time, our products are designed and configured for the U.S. market, operating on 110V electrical systems and meeting U.S. safety standards.

We may be able to accommodate international orders on a case-by-case basis.
If you are located outside the United States, please contact us to request a custom shipping quote.


Damaged Shipments

Please inspect your order upon delivery.

If you notice any damage:

  • note it with the carrier before signing
  • or refuse the delivery if damage is severe

If you accept the delivery:

👉 Take clear photos of:

  • the packaging
  • the damaged product

Then email us immediately at:

👉 support@clearflowpoolsupply.com

We will work with you quickly to resolve the issue.


Returns

For full details on returns, please visit our Returns Policy page.

Why Buy from Us

Why Buy From Us

We understand—you have options when it comes to buying pool equipment online.

At ClearFlow Pool Supply, our goal is simple:

👉 provide reliable products
👉 offer a straightforward buying experience
👉 and support you every step of the way

Here’s what sets us apart.


Free Shipping Across the U.S.

No hidden fees. No surprises.

All orders ship free within the United States, including large and heavy equipment.


Competitive Pricing

We work to offer strong, competitive pricing across our entire catalog.

If you find the same product available online at a lower total price, feel free to reach out—we’re happy to review it.


30-Day Return Policy

If your product isn’t the right fit, we offer a 30-day return window.

We aim to make the process as simple and straightforward as possible.
(See our Returns Policy for full details.)


Reliable Equipment

We focus on products that matter:

  • durable
  • proven
  • built for long-term use

Our goal is to help you avoid the frustration of unreliable or low-quality equipment.


Customer-Focused Support

We’re here to help before and after your purchase.

Whether you’re:

  • replacing a component
  • upgrading your system
  • or choosing equipment for the first time

👉 we’re here to make the process easier


Our Commitment

We stand behind what we sell.

If something isn’t right, we’ll work with you to resolve it quickly and fairly.


Price Match Policy

If you find the same product offered at a lower total price (including shipping), contact us at:

👉 support@clearflowpoolsupply.com

We’ll review the offer and do our best to match it.

Description
✓ Authorized Dealer ✓ Free Shipping ✓ Manufacturer Warranty ✓ Expert Support

The Pentair CS400™ Semi-Automatic Backwash Controller for 5-Tank Systems simplifies the backwash cycle of Stark™ and THS Series® commercial filtration systems equipped with diaphragm-valve face piping kits. With Acu-Trol® Intelligence, this programmable controller can backwash up to six filters in sequence via an integral multi-port pressure distribution valve — saving water, energy, and operator time on every backwash cycle.

A backwash can be initiated three ways: single-touch semi-automatic button, external signal from a master controller such as the Acu-Trol AK600, or an optional differential pressure switch for automatic backwash functionality. Features user-configurable settings, automatic calculated backwash cycle time, stored backwash data and history, alarms, heater cool-down (Fireman's delay), and valve control for pump and heater protection. Compatible with Acu-Trol AcuPort™ for network connectivity.

Key Features

Three Backwash Initiation Modes

Single-touch semi-automatic, external signal from AK600 master controller, or optional differential pressure switch for basic automatic operation.

Up to 6 Filters in Sequence

Integral multi-port pressure distribution valve actuates diaphragm-style backwash valves using city water pressure or compressed air — up to 6 filters per cycle.

"Advance" Feature — Water and Energy Savings

Skips unnecessary backwash cycles — one of the most eco-friendly commercial backwash controllers on the market.

Acu-Trol® Intelligence

Automatic calculated backwash cycle time, stored backwash data and history, user-configurable settings, and alarms.

Heater Cool-Down (Fireman's Delay)

Valve control ensures pump and heater protection prior to backwash cycle start — standard safety sequence.

Network Connectivity

Connect to networks via optional Acu-Trol AcuPort™. Compatible with Acu-Trol AK600 multi-body water chemistry and pump room controller.

LCD Display

Clear LCD interface for programming, monitoring, and alarm status.

Compatible with Stark™ and THS® Filters

Designed for Stark™ and THS Series® filtration systems with diaphragm-style backwash valves.

Who It's For

  • Commercial aquatic facilities operating Stark™ or THS Series® filter systems with diaphragm-valve piping kits
  • Filter rooms with up to 6 filters requiring automated or semi-automated backwash sequencing
  • Operations integrating with Acu-Trol AK600 master controllers or AcuPort™ network systems
  • Facilities seeking to reduce backwash water consumption and energy costs through intelligent cycle management

Specifications

Controller

Max Filters Supported Up to 6 in sequence
Compatible Filters Stark™ and THS Series® with diaphragm-valve face piping kits
Backwash Initiation Semi-auto (button), external signal (AK600), differential pressure switch (optional)
Valve Actuation City water pressure or compressed air
Display LCD
Color Blue

Physical

Product Weight 25 lb
Shipping Dimensions 18 × 20 × 24 in

Warranty

Warranty 60 Days

Warranty

The Pentair CS400 Backwash Controller comes with a 60-day manufacturer warranty. Clearflow Pool Supply is an authorized Pentair dealer and will assist with any warranty service needed.

Frequently Asked Questions

What is the difference between semi-automatic and automatic backwash?

The CS400 is a semi-automatic controller — a backwash cycle requires a human action to initiate (pressing the button or receiving an external signal). With an optional differential pressure switch added, the controller can trigger automatically when filter pressure rises to a set threshold, providing basic automatic backwash functionality without full automation equipment.

Is this compatible with all commercial filter systems?

No. The CS400 is specifically designed for Pentair Stark™ and THS Series® filtration systems equipped with diaphragm-valve face piping kits. It is not compatible with other filter types or brands. Confirm your filter system's piping kit configuration before ordering.

Shipping

Shipping Policy

At ClearFlow Pool Supply, we keep things simple.

👉 Free shipping on all orders within the United States.
No hidden fees. No surprises.


Order Confirmation

As soon as you place your order, you’ll receive an order confirmation email.

This means:

  • we’ve received your order
  • your payment method has been pre-authorized

Once your order is in our system, we verify:

  • product availability
  • inventory status with our suppliers

If an item is unavailable or backordered, we will:

  • void the pre-authorization
  • contact you promptly to discuss alternatives

If your item is in stock and ready to ship (typically within 3–5 business days), your order will be processed and prepared for shipment.


Order Shipment

Orders that are in stock will typically ship within 3 business days.

You will receive a shipping confirmation email with tracking details within 24 hours of your order leaving the warehouse.

If you do not receive tracking information within 4 business days, please contact us at:

👉 support@clearflowpoolsupply.com 


Shipping Scope

We currently ship to customers within the United States.

Due to the size and nature of many pool equipment products, some orders may ship via freight carriers. Delivery times may vary depending on location and product availability.


International Orders

At this time, our products are designed and configured for the U.S. market, operating on 110V electrical systems and meeting U.S. safety standards.

We may be able to accommodate international orders on a case-by-case basis.
If you are located outside the United States, please contact us to request a custom shipping quote.


Damaged Shipments

Please inspect your order upon delivery.

If you notice any damage:

  • note it with the carrier before signing
  • or refuse the delivery if damage is severe

If you accept the delivery:

👉 Take clear photos of:

  • the packaging
  • the damaged product

Then email us immediately at:

👉 support@clearflowpoolsupply.com

We will work with you quickly to resolve the issue.


Returns

For full details on returns, please visit our Returns Policy page.

Why Buy from Us

Why Buy From Us

We understand—you have options when it comes to buying pool equipment online.

At ClearFlow Pool Supply, our goal is simple:

👉 provide reliable products
👉 offer a straightforward buying experience
👉 and support you every step of the way

Here’s what sets us apart.


Free Shipping Across the U.S.

No hidden fees. No surprises.

All orders ship free within the United States, including large and heavy equipment.


Competitive Pricing

We work to offer strong, competitive pricing across our entire catalog.

If you find the same product available online at a lower total price, feel free to reach out—we’re happy to review it.


30-Day Return Policy

If your product isn’t the right fit, we offer a 30-day return window.

We aim to make the process as simple and straightforward as possible.
(See our Returns Policy for full details.)


Reliable Equipment

We focus on products that matter:

  • durable
  • proven
  • built for long-term use

Our goal is to help you avoid the frustration of unreliable or low-quality equipment.


Customer-Focused Support

We’re here to help before and after your purchase.

Whether you’re:

  • replacing a component
  • upgrading your system
  • or choosing equipment for the first time

👉 we’re here to make the process easier


Our Commitment

We stand behind what we sell.

If something isn’t right, we’ll work with you to resolve it quickly and fairly.


Price Match Policy

If you find the same product offered at a lower total price (including shipping), contact us at:

👉 support@clearflowpoolsupply.com

We’ll review the offer and do our best to match it.