Question
I live in Tarpon Springs Florida (West Central Florida) and I have St. Augustine grass that I can not get green enough and it "crakles" when I walk on it.  I fertilize and have Tru Green com on a quarterly basis.  I recently had a "bank" of dollarweeds infestation and was told it was from too much watering.  The local home depot specialist told me of chemicals to get rid of them, but this only made them prosper and look very healthy.  Please help.  

Answer
This under-researched weed ='s days may be numbered after all.  The Turfscience website (http://turfscience.com/weeds/dollarweed.html) broadcasts the bad news about this bad weed, which it calls "the most serious weed of St. Augustine lawns in Florida", with an overview of work being done for homeowners like you, as well as golf greens managers and other turf managers who don't like it.

Testing the traditional theory that you can manage Dollarweed in a St. Augustine lawn by controlling the amount of water it gets, Turfscience reports that the experiment uses 3 different watering schedules: high (daily), moderate (weekly soaks in response to wilting), and low (quick splashes in response to wilting).

Although the research is not completed yet, preliminary results look positive for homeowners.  It looks like it's worth trying this at home.  

The perennial Dollarweed (Hydrocotyle umbellata), which we homeowners north of the Mason Dixon line call Pennywort, grows from Maine to Florida and West to California.  It is said to thrive in moisture and languish when an area is dried out - difficult to do in Tarpon Springs.

For less enlightened homeowners, the Weedalert.com website, which is geared to lawn professionals (http://www.weedalert.com/weed_pages/wa_dollarweed.htm), posts a chart (http://www.weedalert.com/cgi-bin/recs_view.cgi?weed=30) of ways to chemically annihilate this ubiquitous pest.  How effective they are at that, I cannot say.

Me, I prefer to do things the old fashioned way, sans Agent Orange, so that we can watch our dogs roll around in the grass with no fear of genetic twists and long term liver disease.  Birds can sift through my grass for bugs and still produce healthy offspring with 2 wings, 1 head, etc.  The soil structure likes it, too - microbes flora and fauna that would not survive a chemical attack thrive and complete Nitrogen and Carbon cycles in our yard year round.

There is a lot of discussion about ways to get rid of this pest.  Despite rumors to the contrary, the Dirt Doctor, who has a website that (http://www.dirtdoctor.com/forum/archive.php/o_t/t_3056/dollar-weed.html) and a radio show in the Southwest, has not endorsed the use of table sugar as an herbicide, most obviously not to eradicate Dollarweed.  

Some bloggers tout the use of Greese to eliminate Dollarweed, claiming these aquatic birds can't get enough of the stuff.  You can apparently even rent a Goose for this purpose in some municipalities.  Others shrug that solution off.

Other researchers are studying the water torture to rid grass of Dollarweed: "Does reduced irrigation reduce dollarweed?"  A one-half acre site was planted with Hydrocotyle umbellata and St.  Augustinegrass plugs...Hypothesis is that moderate irrigation will control dollarweed invasion.  Their study, however, is still not done.

Sodding is sometimes an option for bad infestations .  Sod may begin as a clean slate, but unfortunately it is quickly invaded as the Dollarweed grows through the sod and bounces back.  

Hard to believe, but this weed is considered endangered in 3 states.  

So the bottom line is, try watering less, and perhaps drying out the turf with clear plastic to shield it from rain.  Hand weed the stragglers who seem to escape.  At this point in history, unfortunately, there are not many options for dealing with it.

Remember, a strong St Augustine lawn is probably the best offense in this war.  That one-two punch is your best bet right now.  Frankly, my money says that if you do, you may be pleasantly surprised.  Not a miracle cure, but good enough.  Let me know what you decide to do, if anything, and what results you get.