Is there a specific reason you are adding those powders in particular?
What size of tank is it, and what water changes does it get? Need to know so we can advise on the amount of ferts to use

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Most plant foods are mainly just traces, the reason the one in that auction and Tropica Plant Nutrition + are said to be so good is because they also provide NPK nutrients. But it's much cheaper and more flexible to use dry powders for this.
Tetrapond Plantamin will be enough for the plants trace elements (though it's more expensive than just buying powdered trace elements).
Can you remember exactly what chemical the potassium mix is? Depending on what the "potassium mix" is, it will probably do for the "K" (potassium) part of NPK fertilisation.
Calcium phosphate is something I've never seen being used before, are you sure it's not calcium
sulphate? If that's what it is, it's unlikely the plants need it

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The "magnesium mix" is probably magnesium sulphate (epsom salts), you can buy there for a couple of £ from a pharmacy, and may not be needed but you may as well use them if you have them.
So that leaves the "N" (nitrogen) and "P" (phosphate) parts of NPK fertilisation to be covered. If the tank has low-medium light and lots of fish/shrimp, then their waste will likely provide enough of this.
If you don't think the plants are getting enough N and P (look for signs of deficencies here:http

/www.aquaessentials.co.uk/index.php?main_page=page&id=8&chapter=0) you can buy a couple of powders for less than £10 that will you years depending on the tank.