I have a numbers of farms that are changing there nutrient inputs over to compost (and balancing minerals) which they are making onsite. We are wanting to get comments back in regards to, is it necessary to also use compost teas and the ex tra capital to purchases brewer. An if so there is a number of these brewers available all saying there system is the best, but which one??

well looks like no one has and reply ???
or or am I missing some thing on the page to link me to any replys

It is not necessary to use compost tea, but it is useful.

It is a good way of making a small amount of compost go further It has Particular benefit for control of leaf diseases on susceptible plants It is often easier to apply than solid compost.

At least until you get considerable experience, go for a very simple system. You just need a tank and a pump. Do not use chlorinated water (or drive it off by running through the pump for a few hours prior to adding ingredients)

Use your own recipe, or this one:
1 kilo compost
200grams vermi cast
50-100ml molasses (to make a bacterial rich tea) or 100 ml liquid seaweed and/or humate (to grow fungi)
15 litres of water

other peoples systems may be very good, but they can be expensive. Like most things, it is probably better to gather some experience at the cheaper end then decide how you want to improve your system.