As long as you give it a healthy stir before your use it it will be fine. From what I understand the longer you leave it the stronger the fertilizer will be. I'm guessing the aerator won't hurt but is not a necessary step.
Also, I'm not sure what you mixture is exactly but here is my source:
DIY Seaweed Liquid Fertiliser
Not sure if many people here use seaweed as a fertiliser, I it's for outdoor grows mainly but as an organic fertliser its a great thing to add to plants. The best way to use it is in its dry form as a mulch or as a foliage spray in liquid form.
This liquid form is very easy to make so I thought I'd share it, it takes a bit of time but once you're done, you're cruising.
Go down the beach and collect a ton of seaweed, check your local laws you don't wanna get busted for raiding the beach, although I'm sure not many of us care about that here. Collect as much as you think you can fit into whatever container you decide to use. You can use any size container, just remember, the bigger the container, the more fertiliser you will have.
Take your seaweed home and give it a rinse to remove excess salt. Next fill your container 2/3 of the way full with water. Tap water is fine since its going to be left sitting for a while anyway. Next grab your seaweed and shove as much in the container as you can without the water overflowing.
Next simply cover your container and let mother nature take care of the rest. Giving it a stir once in a while will help spread nutrients into the water evenly but really as long as you give it a stir before you decide to use it, you'll be fine. Leave it for a minimum of three weeks and then it's good to go. Just remember, the longer you leave it the stronger your fertliser will be.
Seaweed is high in Potassium and is also used as an organic pesticide so use a spray bottle and give the leaves a misting every few days in the flowering cycle if your plants need the extra potassium boost.
Also here is the link to the forum from which the info came.
https://forum.grasscity.com/organic-grow ... liser.html
Mods I hope this is within the rules and if not I totally support my post being removed.
Also my apologies if I am breaking any rules.