Yes you fill the container up.  It will be over the 26 line (by about 4 ounces) because it is a quart size sprayer (by Gilmour).  It really wont make that much difference.  It is a 12.5% solution, that when used with a 4:1 hose end sprayer, treats your lawn at 3.13%. I know that’s a little technical, but a few ounces over or under wont make a huge difference. The sprayer will put out 20 gallons of solution which covers about 4-5,000 square feet. I remember you have ants, so really soak everything down. Have fun!