It's seaweed concentrate, from what I've found online, Seasol alone is not enough of a plant food to keep your plant fed.
Emilya was 100% correct, a combination of water pooling and a bad pot was the problem.
I've now repotted her into a 1.5l rocket pot with two parts Canna Terra Pro and 1...
Do you think I could repot into a non self watering pot without causing to much damage?
I have these pots which are 100mm, I also have an air pot for when it gets much bigger.
I use this moisture meter as well as the first knuckle method, watering on average is about 3 days, so I wait until it's barely moist before watering again. Water is 1.5ml seasol to 500ml demineralised water