I'm not familiar with it, but let's compare the labels.

Weathermax active ingredient is "Glyphosate, N-(phosphonomethyl)glycine, in the form of its potassium salt 48.8%". It also says "Contains 660 grams per liter or 5.5 pounds per U.S. gallon of the active ingredient glyphosate, in the form of its potassium salt."

Super Concentrate active ingredient is "Glyphosate, isopropylamine salt 50.2%". No pounds-per-gallon info on that label. But Roundup PRO Concentrate active ingredient is "Glyphosate, N-(phosphonomethyl)glycine, in the form of its isopropylamine salt 50.2%", which to my naive eye looks the same as Super Concentrate. That label goes on to say "Contains 600 grams per liter or 5 pounds per U.S. gallon of the active ingredient glyphosate, in the form of its isopropylamine salt.".

So Weathermax looks to be effectively 10% more concentrated than Super Concentrate. Hopefully someone more knowledgeable will correct this if I'm wrong.

Just the price of regular weed killer tells me I can pull a lot od weeds before I can justify that cost. Spending $150.00 on something that contributes to the pollution of my world is not something I would do.

I figure this product is an amazing bargain. One gallon of Roundup Super Concentrate costs a little over $100 retail. The same amount of active ingredient in 2.5-gallon Weathermax costs $55.

The product label online ("provided for general information only") does in fact give instructions for use in handheld sprayers. It's got application percentages for a wide variety of weeds, and a chart giving ounces/gallon to yield various percentages.

Two points:

1.Technically this particular formulation is an agriculturally labeled product, and as such is illegal to use around the house and garden, unless it is a farmstead.

2.While many pesticides can move off site and create problems, use of this product as directed on the label should not contribute to the pollution of the world. Once applied, glyphosate and the formulation's surfactant will bind tightly to soil particles until it they are completely broken down by microbes in the soil into natural substances.

From the ENVIRONMENTAL FATE OF GLYPHOSATE, Jeff Schuette Environmental Monitoring & Pest Management, California Department of Pesticide Regulation:
Glyphosates primary route of decomposition in the environment is through microbial degradation in soil (Franz et al. 1997). The herbicide is inactivated and biodegraded by soil microbes at rates of degradation related to microbial activity in the soil and factors that affect this activity (Eriksson, 1975). The biological degradation process is carried out under both aerobic and anaerobic conditions by soil microflora. Rates of decomposition depend on soil and microfloral population types. A study on the effects of glyphosate on microbial biomass (Stratton G. and Stewart K. 1992) found glyphosate generally had no significant effect on the numbers of bacteria, fungi or actinomycetes in forest soil and overlying forest litter. There was no effect of glyphosate on in situ respiration in most of the treated systems while the remainder showed a increase in respiration. Muller et al. (1981) found that glyphosate degrades at very low temperatures and does not adversely affect nitrogen fixation, nitrification or denitrification activity.
Conclusion: Glyphosate is a non-selective, non-residual broad-spectrum, foliar applied, postemergence herbicide that is highly effective against emerged grasses, brush and broad-leaf weeds. The summarized studies indicate that glyphosate is adsorbed to mineral clays and organic matter and is excluded from these sites by inorganic phosphate. Glyphosate has limited preemergence herbicidal activity in most soils because of its tendency to adsorb strongly to soil. A low Koc is an indication that glyphosate will not move readily through soil, and under conditions of the summarized studies, glyphosate would not leach into non-target areas. Glyphosate is inactivated in soil and water by microbial degradation. When applied to foliage, glyphosate is readily absorbed and translocated to various parts of plant via the phloem. Recent data indicate that glyphosate appears to be relatively nontoxic to mammals, birds, and fish and shows no signs of bioaccumulation in the food chain.

EPA Ground and Drinking Water document for glyphosate:
Glyphosate is most often applied as a spray of the isopropylamine salt and is removed from the atmosphere by gravitational settling. After glyphosate is applied to forests, fields, and other land by spraying, it is strongly adsorbed to soil, remains in the upper soil layers, and has a low propensity for leaching.
Glyphosate readily and completely biodegrades in soil even under low temperature conditions. Its average half-life in soil is about 60 days.

Thx for the responses. I ended up getting my answer(s) over on the vegetable forum. Its funny how certain people(kimmsr) like to give there unsolicited opinions though...I might expect that in the ORGANIC forum...The next time I need to buy more herbicide, I'll send you a note and see if you would like to come down and hand pick weeds on my 200' gravel drive, around 500 young pine and spruce trees and in my 20x60 garden and along 1/4 mile fence line plus some other areas. Actually I don't think I would want someone like you to come on my property. Happy weeding...

Would you be so kind as to post a link to the vegetable forum thread where you got your answers? Then I (and anyone else who cares) can compare them to the answer I posted here.

Sure,

So how are you actually using your bottle of Weathermax? I don't see any specific guidance in that other thread.

I ended up useing 1 1/2 ounces per gallon. I sprayed "lightly" a week ago Tuesday and the grass & weeds are now toast. I may experiment next with one ounce/gallon. BTW, I used to buy the 1 gallon super concentrate RU for $65 at a flea market - $100 at Lowes. The last two years he only had the regular RU concentrate(6 ounces per gallon) for $15 a quart - $20 at Lowes. Looks like I did okay @ $150/ 2 1/2 gallons.

Daryljurassic, So did you use it on poison ivy and wild blackberry? If so, was it effective? You said grass and weeds were toast above, and I just wondered. I have poison ivy and multiflora rose and would like to find something that will work.