Power Sprayer Tank Agitation: Jet vs. Mechanical, Sizing & Setup
Posted by Andrew Greess on Mar 30, 2026
Key Takeaways:
- Poor agitation causes uneven application rates, tank buildup, clogged filters, and damaged pumps.
- Jet agitation costs less and handles most spray jobs. Mechanical agitation adds roughly $500 to $1,000 but is best for heavy granular or non-soluble materials.
- Most liquid products need agitation flow equal to 8% of tank volume per minute. Granular or non-soluble products need 12%. Agitation jets (3X, 5X) cut that flow requirement.
- Don't plumb agitation on the pump return. Use a separate agitation line with a gate valve.
- Fill the tank and watch the agitation pattern before accepting a rig. Dead spots let material settle.
When it comes to power spray equipment, a well-mixed tank is critical. That's especially true for landscape, turf, and golf applications using products that don't stay dissolved in water, like granular fertilizers and wettable powders. Here's why agitation matters, the two main types of spray tank agitation, how to size your pump for it, and how to set it up correctly.
Why Tank Agitation Matters
Incorrect application rates. If product isn't well mixed, you may apply it at the wrong rate or unevenly. Either way, you won't get the results you want, and you'll waste money on extra product, callbacks, or fixing the damage.
Tank buildup. Unmixed material settles to the bottom of the tank. Left alone, it can harden into a solid mass, and we've seen cases where the tank had to be replaced.
Clogged lines and pump damage. Settled material gets pulled into the plumbing. The filter clogs first, so techs who check it regularly can catch the problem early. If the filter isn't cleaned, the pump starves for liquid and can be ruined, and material can clog hoses, fittings, and spray tips. We've seen fittings completely plugged and pumps destroyed.
Jet vs. Mechanical Agitation
| Jet Agitation | Mechanical Agitation | |
|---|---|---|
| How it works | Sends part of the pump's output back into the tank through jet nozzles | Stainless steel paddles on a shaft, driven by a belt from the engine |
| Cost | Lower; may require a larger pump | Adds roughly $500 to $1,000 to the rig |
| Best for | Most liquid products and many dry products | Heavy granular and non-soluble materials |
| Can it be added later? | Usually yes | Usually no; must be built in |
| Maintenance | Minimal; keep jets clean | Shaft seals and bearings eventually leak and need service |
Mechanical agitation provides excellent, continuous mixing whenever the engine runs. The downsides are cost, the fact that it usually can't be added to an existing sprayer, and downtime when the seals and bearings need service.
Jet agitation is far more common because it costs less and works well for most applications. The main added cost is that you may need a larger pump with enough output to run both the agitation and your spray gun or boom.
How to Size Your Pump for Jet Agitation
Your pump has to deliver your spray volume plus the volume needed for agitation. Use these rules of thumb:
- Liquid products: agitation flow of 8% of tank volume, in gallons per minute (GPM)
- Granular or non-soluble products: 12% of tank volume
Agitation jets reduce the flow you need. Jet nozzles use a venturi effect to multiply the mixing action, usually 3X, 5X, or 7X. Divide the agitation requirement by the multiplier. The number of jets doesn't change the calculation.
Example: liquid product in a 200-gallon tank
8% × 200 gallons = 16 GPM for agitation
With 3X jets: 16 ÷ 3 = about 5.3 GPM
Spraying at 5 GPM? You need a pump that delivers at least 5 + 5.3 = 10.3 GPM.
Example: granular product in a 200-gallon tank
12% × 200 gallons = 24 GPM for agitation
With 3X jets: 24 ÷ 3 = 8 GPM more than your spray volume.
Choose a pump rated above your calculated total. Pump ratings assume a new pump with no restrictions, so real-world output is almost always lower. If the pump can't supply both, you won't be able to agitate while you spray.
Shop Hypro 3X agitation jets (3371) and Hypro 5X agitation jets (3371-0028).
How to Plumb Agitation
Some sprayer builders plumb agitation on the pump's bypass return line. We strongly recommend against it. Some pump manufacturers, including Hypro and Udor, specifically warn that it creates back pressure that hurts pump performance. And because return lines can't have shut-off valves (centrifugal pumps are the exception), servicing the pump with a full tank means dumping the tank.
Instead, use separate lines: the bypass return to the top of the tank, and the jet agitation line to the bottom. A gate valve on the agitation line makes it easy to adjust agitation, and it doubles as a simple way to adjust spray pressure. More agitation means less pressure at the gun.
Positioning Agitation Jets
Use enough jets to stir the whole tank, and position them so there are no dead spots where material can settle. Don't aim any jet toward the pump's suction pickup, because that can interfere with the pump intake. Before accepting a new rig, fill the tank with water and watch the agitation pattern.
Mix Tanks
If you run several sprayers and apply a lot of material, a separate mix tank can make sense. These are cone-bottom tanks with a dedicated high-volume pump, usually centrifugal, gas or electric, that churns product into water and then pumps the mix into your sprayers. When selecting one, choose a pump with readily available parts, make sure the cone-bottom outlet has an anti-vortex fitting so material drains properly, and plumb the pump and hoses with cam-lock fittings so one pump can fill, mix, and empty the tank.
Pre-Mixing for Older Equipment
If you're running an older sprayer with weak agitation, pre-mix your product in a bucket of water before adding it to the tank. If the rig has a spray hose and spray gun, spray back into the tank to help mix it.
Need a Sprayer with the Right Agitation?
We build power sprayers in our Phoenix shop with the pump and agitation sized for what you spray, including weed and tree sprayers for granular and fertilizer work. Request a quote or call 602-371-1993.