For those of you who saw the video I just made on spraying a 6,600 sq ft lawn with a 2 gallon sprayer, that video is just the background - the teaching part. I hope you appreciate that I share with you these more advanced teachings. I think it's important for those of you who have been doing this for a while to learn how to flex so that your lawn care becomes easier over time - and for sure, getting more sq footage done in a single fill up of the sprayer is a big time saver.
Here is the math:
First Check That You Are Ok With Dilution Ratio
Minimum Dilution Rate: 7:1
That means that your mix has to be at least 7 parts water and 1 part concentrate which equates to 8 total parts.
I am using a 2 gallon sprayer which can hold 256 ounces.
Note: 1 gallon = 128 ounces
256 ounces / 8 parts = 32
This means that each part of the mix is 32 ounces. If the dilution ratio is 7:1 that means the concentrate in the sprayer can represent up to 32 ounces and I'm still be within labeled guidelines.
Our application rate on the RGS is 3oz/1000.
So the next thing I need to know is how big of an area I am treating and that is why lawn measuring is so important and is the very FIRST thing you do when starting any lawn program. In this case, I'll be treating my church Bermuda section and that is 6,600 sq ft.
Since our application rate is 3oz/1,000 sq ft, we know we will need 19.8 oz of concentrate to cover the lawn space. Here is the math on that:
6.6 x 3 = 19.8
Remember, the "application rate" is telling you how much concentrate needs to get sprayed evenly across each 1,000 sq ft of lawn area. We have 6.6 of those areas because we have 6,600 sq ft.
Now you should be able to see that since you need 19.8 oz of concentrate you are well under the 32 oz that you were allocated in the dilution ratio above.
So we are good there, but now we need to make sure we can actually walk that area with enough speed to actually get the spray mix out across the space. 6,600 sq ft is a decent sized area - in other words, it's a lot to walk and if your sprayer runs out of product before you finish then your app won't be correct - it will be too heavy and some areas will be missed. So we have to find a way to restrict the flow, or slow it down, so we can keep up.
Typically, I like to spray 1,000 sq ft per minute. That is pretty fast but I can do it with my stubby 5'8" frame and in fact, I can even go faster if I want to. Because I have experience "putting some ass into it" and have done it before, I know I can spray 6,600 sq ft in 5-6 minutes with no problem. I'll be breathing heavy but as many of you noted in my prodiamine video, I need to exercise anyway.
Now To The Tips
The brown FloodJet tip puts out .35 gallons per minute at 20 PSI. PSI stands for "pounds of force per square inch" and at 20PSI the brown floodjet tip will allow .35 gallons of liquid to come from the sprayer.
I got the PSI from the Amazon Listing for the sprayer where it tells me it puts out 20PSI. Every sprayer is different because they all have different pumps. Some are variable, others, like this Field King, are fixed.
Since we know I have 2 gallons of spray mix available to me, then I can do some math to know how long it's going to take this sprayer to "pump out" or empty:
2 / .35 = 5.71
That's 5.71 minutes. You could call it "good" here and assume 5 and three-quarter minutes but if you want to be exact just convert that .71 to seconds like this:
60 seconds x .71 = 42.6
So now we know that with the brown tip, the Field King 2 gallon sprayer is going to pump out in 5 minutes and 43 seconds.
Can you walk a 6,600 sq ft area in 5 minutes and 43 seconds? You can, but you will have to book it pretty good!
In the next video I'll be showing you how to do it, as well as putting down my first fert app of the season.
Final Note: some of you may ask if the Pennant Magnum pre-emergent has a dilution ratio requirement. It isn't specific but simply reads:
"Apply Pennant Magnum in sufficient carrier to obtain thorough coverage"