Could anyone please advise us of where we could get some info, on what would be a safe weed killer to use on our finca how much we might need per acre, where we can buy it and the best way to apply it,
we were thinking of strimming and then weed killing the land but we are new to this so any one with experience of this could maybe shed some light on this subject as we seem to have an abundance of weeds appearing and we would like to tidy up before it gets to much.
Cheers.  

OK, We have tried neat bleach, it works ok-ish, and kills pretty quickly, but the weeds come back as strong as ever and thank you for the drink.
We were going back to Round-up but as it's now 65 euros for 5ltrs thats a non starter, so we have tried Glifosato at a much more reasonable 39 euros, and although it still takes 3-4 days to work, we think it is better than the Round-up.
We bought from Sol D'Ebre in Tortosa.

Those goats don't eat everything our local pastor does our land but they always leave the thistles alone!!

As a goat owner I can confirm the untruth of goats eating anything. In my experience they only eat the things you don't want them too and leave the rest! Whilst on the subject is there anyone else on the forum keeping goats? I have a fine billy available for breeding or I would be interested in swapping Billies for breeding purposes.
Bruixot

PS Donkeys seem to be better at clearing undergrowth and thistles in my personal experience.

I've been here three and a half years now and have four hectares that have been neglected for years so I know something about weeds.  You'll have to accept that weeds are a major factor here.  Just look at the agricultural (and wild) land around you.  The local farmers accept weed control as routine.  I've tried most available methods and the best method depends on several factors.  One is the area you need to treat (bearing in mind it will have to be repeated on a regular basis).  Using bleach would not be practical on a large sacle.
Roundup and Glyfasato (spelling ?) have been mentioned.  They're the same thing but Roundup is rather expensive.  All the co-operatives (including Sol D'Ebre) sell Glyphosate products.  The price has varied a bit over the last couple of years but averages about €40 for 5 litres.  That having been said.  That's enough to treat a very large area at the correct dilution (about 5 hectares at a dilution of 1% i.e. 100ml in 10litres of water).  Apparently there is no advantage in using a stronger mix.  I've found it can take a week for there to be any visible sign of wilting and several weeks for the weed to look completely dead.  Also, some weeds succumb more readily than others.  If I'm going to treat an area that hasn't been done for a while where the everage weed height is say half a metre, I strim/brushcut first then wait a week or two for new growth to emerge before spray.  This is because if you just spray, you will still be left with upright dead weeds that look even worse than when they were green.  You'll find that at this time of year, with a bit of patience, the dead weeds will gradually crisp in the hot sun and gradually crumble away.  Be aware though that any decent rain fall will soon set off fresh growth so it's rather like painting the forth bridge.  A fact of life out here.  I'll continue this in a second post as the screen is playing up.

With Glyphosate (Round up etc) the finer the spray applied has a better effect, don't soak leaves, mix is 50/1 on normal 36% (?) concentrate. There is a battery (AA) operated attachment for a backpack that delivers a fine constant mist, you save money this way too. Personally I've gone organic except for under the trees that will be harvested, enjoy the colour & wildlife, no more soil erosion & when it gets too much strim it all down, takes just as long as constant spraying! My opinion anyway.
Paul

I have a 15 litre spray tank how much round up do I put into 15 litres
thanks

The guy in Sol debre told me 200ml in 16 litres and my neighbour who has farmed up here for donkies years and has perfect land ( you could eat your dinner off it )
uses the same ratio.