K-Rain K2 vs. ProPlus vs. Rain Bird Maxi-Paw: Purple Septic Sprinklers Explained
What's the difference between K-Rain K2, K-Rain ProPlus and Rain Bird Maxi-Paw purple-top sprinklers? All three are used for non-potable irrigation, including properly designed aerobic septic spray systems, but they work differently and have different adjustment controls. K-Rain K2 SmartSet and ProPlus are gear-driven rotors; the Rain Bird Maxi-Paw 2045A-NP is an impact sprinkler.
This guide compares the purple-top models sold by Septic Stop and explains, using the manufacturers' instructions, how to change spray distance (radius) and spray angle (arc) for quarter-circle, half-circle and full-circle coverage.
Compare the three purple-top sprinkler heads
These are the three models currently listed by Septic Stop. Select a photograph or product name to see its specifications and replacement options.
Rain Bird Maxi-Paw 2045A-NP
Impact rotor
20°–340° or full 360°
Approx. 22–45 ft radius
Photo: Septic Stop
Actual coverage for every model depends on installed nozzle, operating pressure and field conditions.
| Feature | K-Rain K2 RCW | K-Rain ProPlus RCW | Rain Bird Maxi-Paw NP |
|---|---|---|---|
| Drive type | Gear | Gear | Impact arm |
| Adjustable arc | 40° to continuous 360° | 40° to continuous 360° | 20°–340°; separate full-circle mode |
| Arc control | Top dial | Top dial | Trip collars and trip pin |
| Listed radius | 20–48 ft | 28–50 ft | 22–45 ft |
| Pressure range | 20–70 psi | 20–70 psi | 25–60 psi |
| Water inlet | 3/4-inch bottom | 3/4-inch bottom | 1/2- or 3/4-inch bottom; 1/2-inch side |
What they have in common: All three offer adjustable coverage and purple non-potable identification. That does not mean they automatically deliver the same gallons per minute, coverage area or precipitation rate. Always check the installed nozzle and the actual pressure at the sprinkler.
What do quarter-, half- and full-circle spray patterns mean?
The arc determines which direction the sprinkler sprays as it rotates. It does not directly determine how far the water travels. Here is a simple top-down illustration:
These drawings explain arc only; they are not a site-specific septic spray-field layout. A 90° pattern typically covers one-quarter of a circle, while 180° covers half. On the K-Rain models, selecting 360° results in continuous rotation. On the Maxi-Paw, full-circle operation requires moving its trip pin into the full-circle position.
How to adjust a K-Rain K2 SmartSet purple sprinkler
The K-Rain K2 SmartSet RCW is a gear-driven reclaimed-water rotor. The purple model listed by Septic Stop includes a pre-installed 3 GPM low-angle nozzle. Other K2 configurations may ship with different nozzles.
Adjust the spray angle (arc)
- Locate the arc adjustment slot on the sprinkler's top.
- Find the left starting position: turn the nozzle turret to its right stop and then all the way left. The nozzle arrow now indicates the fixed left start.
- If the left start does not face the desired direction, use a K-Key to lift the riser, hold the turret still and carefully rotate the lower riser to aim the starting position.
- Insert the K-Key or a flat-blade screwdriver in the arc adjustment slot. Turn clockwise to increase the arc or counterclockwise to decrease it.
- Use approximately 90° for quarter circle, 180° for half circle or 360° for continuous full-circle rotation. Confirm the actual pattern during a test run.
Adjust the spray distance (radius)
- Locate the nozzle retention / stream-breakup screw near the nozzle.
- With the head operating and only when it is safe to approach without wastewater exposure, turn the screw gradually clockwise into the water stream to break up the jet and reduce throw. Keep it secure without blocking the nozzle excessively.
- Turn the screw back out gradually if more distance is needed. If a larger change is required, select the appropriate manufacturer-rated nozzle rather than relying solely on the screw.
View K-Rain's K2 SmartSet adjustment instructions (PDF) →
How to adjust a K-Rain ProPlus purple sprinkler
The K-Rain ProPlus RCW is also a gear-driven rotor with a top-mounted easy-arc adjustment. Its interchangeably sized nozzles provide flexibility for different flows and spray distances.
Adjust the spray angle (arc)
- Rotate the nozzle turret to the right stop, then back to the left stop to find the left start.
- Use the K-Key to lift the riser if the fixed left start needs to be reoriented; hold the nozzle turret and rotate the lower riser.
- Insert the K-Key or flat screwdriver into the arc set adjustment slot on top.
- Turn clockwise for a larger arc or counterclockwise for a smaller arc, aligning with 90° (quarter circle), 180° (half circle) or 360° (full circle) as needed.
- At 360°, the ProPlus rotates continuously clockwise. Confirm the spray does not extend beyond the approved irrigation area.
ProPlus top markings help identify arc settings. Photo: Septic Stop.
Adjust the spray distance (radius)
- Locate the nozzle-retention / breakup screw beside the nozzle.
- With the head operating and safe to access, advance the screw gradually clockwise into the stream to shorten and diffuse the throw.
- Back it out to restore distance, or select a different approved nozzle to make a larger change in throw or application rate.
View K-Rain's ProPlus setting instructions (PDF) →
How to adjust a Rain Bird Maxi-Paw purple sprinkler
The Rain Bird 2045A-NP Maxi-Paw is a pop-up impact rotor rather than a gear-driven rotor. Its arm makes the familiar clicking motion, and its pattern is controlled by trip collars and a trip pin, not a K-Rain-style arc dial.
Set a quarter-circle or half-circle pattern
- Locate the mechanical trip pin and two adjustable trip stops/collars on the impact sprinkler assembly.
- Move the trip pin DOWN for adjustable part-circle operation, as specified in Rain Bird's instructions.
- Move the two trip stops to mark where the sprinkler should reverse. Set the stops roughly 90° apart for quarter-circle coverage or 180° apart for half-circle coverage.
- Check the actual coverage during operation and fine-tune the stops so the stream stays within the intended area.
Set full-circle coverage
- Move the trip pin UP to disengage part-circle reversing.
- The head will rotate through a complete 360° pattern. The trip collars do not set the full-circle mode.
Adjust the spray distance (radius)
- Locate the diffuser screw in front of the water stream near the nozzle.
- Advance the diffuser screw gradually into the stream to reduce the throw and break the jet into smaller droplets.
- If more throw is needed, back the screw away from the stream. For changes beyond the adjustment range, match an appropriate Rain Bird nozzle to your pressure and flow.
Rain Bird lists a 22–45 ft operating radius for the 2045A, with reduction to about 18 ft possible using the radius reduction screw, depending on configuration and operating conditions.
View Rain Bird's illustrated Maxi-Paw adjustment instructions → | Official Rain Bird product specifications →
Can you replace one brand with another?
Potentially, but similar-looking purple covers do not make heads interchangeable. Before substituting a K-Rain K2, ProPlus or Rain Bird Maxi-Paw, confirm the following:
- Connection: The K-Rain models use a 3/4-inch bottom inlet; the Maxi-Paw has a combination 1/2- or 3/4-inch bottom inlet and a 1/2-inch side inlet.
- Pressure and flow: Compare nozzle flow at the actual operating pressure, especially when several heads operate together.
- Arc, radius and precipitation: Make sure the replacement gives the design coverage and application rate — not merely the same general throw distance.
- Site requirements: Maintain setbacks, spray boundaries, required signs or purple identification, and the approved spray area.
Which purple-top sprinkler should you choose?
Choose the K-Rain K2 SmartSet when your design calls for its approved gear-driven rotor specifications and you want the K2's top arc control. Shop K2 purple-top sprinkler →
Choose the K-Rain ProPlus when the ProPlus RCW's nozzle, radius and flow options match your system, and you want gear-driven rotation with top arc adjustment. Shop ProPlus purple-top sprinkler →
Choose the Rain Bird Maxi-Paw when your system calls for an impact rotor and its nozzle and performance characteristics meet the approved layout. Shop Maxi-Paw purple-top sprinkler →
Shop All Septic Sprinkler Heads
Frequently asked questions
What does a purple sprinkler top mean?
Purple is commonly used to identify equipment carrying non-potable or reclaimed water, including aerobic septic effluent. Purple identification does not itself prove the sprinkler is approved for every septic system.
How do I set a K-Rain sprinkler to 90 or 180 degrees?
Set the fixed left start in the direction you want and adjust the top arc control: clockwise increases the pattern, counterclockwise decreases it. Use 90° for one-quarter of a circle and 180° for one-half. Follow the K2 or ProPlus instructions for the actual model.
How do I set a Rain Bird Maxi-Paw to full circle?
Move the trip pin up to select full-circle rotation. For part-circle patterns, move it down and set the trip stops.
Does changing from quarter-circle to full-circle also change the spray distance?
No. Arc is direction; radius is distance. However, changing the arc without matching nozzle flow can alter the amount of water applied to each square foot of the area. Follow your system's approved design.
How do I shorten the spray distance?
K-Rain K2 and ProPlus rotors use a nozzle-retention/breakup screw; the Rain Bird Maxi-Paw uses a diffuser screw. Advance the applicable screw cautiously into the water jet to reduce throw. Confirm that the new pattern still meets required coverage.
Can I put a Rain Bird Maxi-Paw where a K-Rain ProPlus was installed?
Typically, yes. Verify the connection, hydraulic performance, approved spray layout and any applicable authorization. The two models use different drive and adjustment systems and have different overall heights.
Need help finding the correct replacement?
Take a picture of your existing sprinkler head, including its purple top and any model numbers, and contact Septic Stop. We can help identify the available models and specifications. Be sure to confirm the final selection with your installer and local regulatory authority.
Manufacturer references: K-Rain K2 SmartSet Setting Instructions; K-Rain ProPlus Setting Instructions; Rain Bird Maxi-Paw Impact Sprinkler Instructions; Rain Bird 2045A Specifications. Performance ranges are model/nozzle-dependent; consult the current manufacturer literature before modifying a system.
