It won't ruin your lawn, but it's closer to gimmick than actual helpful for your lawn specifically. It's just another version of a DIY type system for homeowners. If you don't want to do a lot of work, it's probably ok. But you also may not get the high end results many people here aim for. More on reddit.com

This why I shop at a local fertilizer place. $18 gets me 50lbs of 33-0-0 No sales tax either since it qualifies as farming supplies. More on reddit.com

If you really want to go the Sunday route, the dandelion doom is just iron and water in a bottle. Because of this it’s going to take a lot to do damage, with that being said I would go the spray bottle route and just spray each dandelion individually. Don’t be suprised if they come back after getting burnt. If you’re wanting to try their fertilizer there’s a lot cheaper ways to do it. For example the “Texas Green” is a 22-0-2 and covers 5,000 sq ft. That treatment will give you 0.15 pounds of nitrogen per 1,000 sq ft. and cost you about $5.40 per 1,000 sq feet while it’s on sale. Or, you go to the local farm store and buy a 50 lb bag of urea 46-0-0 and apply 0.35 lbs per 1,000 Square feet to get the same amount of nitrogen and it will cost you about $0.13 per 1,000 square feet. That’s the power of marketing, nothing special, just a name and a commercial for the same thing and a lot more money. More on reddit.com

Complete waste of money, don't do it. Soil test yourself through your local extension office or Waypoint Analytical. Spot spray your weeds with something like SpeedZone or TZone. Fertilize per your soil test. Based off your location, people on here can help you with seeding in the fall or if you're in the south, a completely different approach. More on reddit.com