Is This Overkill - External Filter.

French isn't really my thing, but it seems to be able to push 1400 litres per hour through the filter. Even allowing for the fact that these quoted figures are far from accurate, this would seem to be excessive for an 80 litre tank. The normal guidelines are between 5 and 10 times the volume of your tank. IE 400-600 litres hour in your case.

If you use this filter as-is you would end up with a washing machine rather than an aquarium. There are 3 approaches here.
1) Buy a smaller filter.
2) Make sure that the filter you buy has an adjustable flow-rate. Some do, some don't; And my French isn't up to determining this from the text.
3) Use very large pipes and nozzles to reduce the velocity of any pump output. This is trickier than the others and can only help a little.

There is a 1000 litres per hour version for 40 euros; A better bet, but a still a little ott.

Thanks for the replies. Sorry the link was in French. I live in France and go between the two languages all the time.

You are probably right, It is excessive. Would anybody care to recommend something that might be more suitable but that would still be useful if go up a tank size to say 125l

That looks like it would suit but I've become fixated on the idea of having a UV element to the filtration.

Thanks for the ideas, I appreciate the help.

I think I have solved my problem. I found a brand new, unused Aquatlantis BioBox 2 complete with 200w heater, 650lph pump and 4 media cartridges (white floss, coarse foam, carbon foam and clay balls) all fixtures and fittings for sale in a brocante (second-hand shop). UK price in RocketAquatics £81 I paid the equivalent of only £24. 

There may be some way to work in a small UV unit into the pump sump. I'm a happy camper. 

Cheating? I just play the cards I'm dealt.