If my light is 95 par at 12"... My Substrate is 18". So does that mean my lights par is 47.5 in my tank?You can find out the PAR info for most commercial brand lights by googling. If you have a non-brand light, you’d have to use a PAR meter. Most carpet plants need around 50 PAR at the substrate, dwarf hair grass being one of them. IME Dwarf hairgrass isn’t the easiest carpeting plant—some easier options would be s repens, dwarf Sagittaria, and crypt parva.
Totally relate to being overwhelmed when you’re getting started, personal experience and persistence are key. I highly recommend https://www.2hraquarist.com/ for some pretty good basic beginner planted tank info. It doesn’t answer everything but it’s a great resource.
What light do you have?
That makes sense. I just stocked my tank with about 25 fish, so maybe they will start to do better. I'll wait before I switch fertilizers I suppose.To be clear the problem with flourish is that it has very little nitrogen in it. Basically its designed for a tank with a lot of fish and not a lot of fast growing plants. The fish provide the nitrogen through their poop. For a tank without fish or a tank with fast growing plants (like carpeting plants) it means you are starving your tank of needed nutrients which is probably why your hair grass is not doing well.
There are a lot of good fertilizer options out there. Personally I don't want a tank that needs my input every day to survive so I use either all in one fertilizer I dose after weekly water changes or I use an auto doser. But other people really like dosing daily and find it helps them keep track of what is going on in their tanks so to each their own.
Anyway since the OP is in the USA I would recommend Nicolg Thrive as the all in one fertilizer. I've been using them for years now and its a really solid product.
To figure out how much light you are producing you can use a lux meter or the lux meter app for smart phone. Take the lux at the same distance from the light as your substrate is from the light. Then divide that number by 80 to get a rough approximation of par. For hair grass you want at least 25 par. Personally I like my light to be around 30-40 for a high tech tank simply because I find this to be enough light to grow anything but not too much that I have to stress about fertilizer being used up before next weeks water change.
My light is 95 par at 12". My Substrate is 18"... Does that mean my light in my tank is 47.5? If so, it seems sufficient... Correct?