Fish tank set up - please help!

[ThistlesAndUnicorns]

Can anyone please tell me what this is for?? It hasn't come with any instructions. It looks like I've set it up properly but this part is spare!

Info is a big vague but it's something that releases 'plant extracts and vitamins' into the water to help with fish skin protection. A healthy/balanced aquarium wouldn't need it (the best protection a fish can have is to live in the right conditions so it's own immune system does the job) but some more details for you on this little device specifically...

ciano.pt/en/produto/fish-protection-dosator/

www.swelluk.com/ciano-fish-protection-dosator?gclid=CjwKCAiA6Y2QBhAtEiwAGHybPeg2xoMJpSJS25sXN46BJ68nGsA3dEWrsTwDerPD4BKsNg6DbFhsLhoClx8QAvD_BwE

p.s. it's sold seperately to your filter so someone's added it as a bonus freebie, I think.

Looks like a very small filter as well. What size is the tank?

Thanks everyone, managed to get it sorted