So for amendments in building a water only mix these are the most important things to think about if you're trying to follow my mix it up and go style. If you're able to compost or "cook" your mix before planting in it than you can approach a little differently, but in my opinion my approach is more conducive to a water only grow.
For nitrogen, you need an amendment that will release it quickly, but you don't want to use it in large amounts or you'll have too hot of soil to plant in right away. Blood meal in small amounts can do this, I prefer alfalfa meal, the N releases quick but not in large amounts. Alfalfa meal also conditions the soil and has a handful of other benefits and nutrition content. You also need longer term N for later in plant life, N is kinda the building block for life forms so it's pretty important. Feather meal, neem seed meal, and your compost all carry slow release N. You can always do repeat applications of your faster N fertilizers if you can't access slow release ones.
For P you need the same, some for now some for later philosophy. All variations of bone meal will release some P after a few days of first getting in there, and will continue to release it through out the grow along with some calcium. I like having crab shell meal as well because it takes longer to break down but ensures that the later plant stages are well taken care of, without the crustacean meals I would do an application on bone meal about a week before I switched to flower.
The lime will provide slow release calcium and Magnesium plus help buffer your pH if you're using peat moss. But I would also add gypsum for the sulfur it provides along with the additional slow release calcium, that will make sure your mag levels never get out of control!
Speaking magnesium, it can be the hardest to keep kicking in a container water only grow. It's really easy to just apply some epsom salts when you water every once and a while, if you're able to order some Langbeinite (they might have it in the store as k-mag or sul-po-mag) not only will you not have to worry about mag, but you won't have to worry about potassium at all!
If you only had those things you already are gonna grow dank bud! Get it danker by adding trace mineral stuff. Kelp meal and rock dust. Some people push kelp meal for potassium but I've always had to way over do it to get adequate K from kelp meals. I much prefer getting my potassium from a mineral source like Langbeinite. The only successful alternative I've had is home-made compost.
You can get your amendments separate! It is a better value and you control the ratios. It is more upfront money. Most all purpose organic vegetable or tomato fertilizer blends are made with these same principles in mind tho, and are a great way to get into organic gardening without having to think to much about everything. And if you are in a situation where you have to get them shipped, they will save you some money.
And remember water only mixes can't always be water only mixes, sometimes you gotta top dress a little fertilizer. You can so teas too, but you can top dress a lot less often, where nutrient teas require more frequent applications. Bigger pots are your best bet. 15 gallon pots or bigger will do best for water only mixes. Anything seven gallons or smaller will require some fertilizer applications.