Which wormer?

[Dumbo]

I have a 16.2hh TB that was last wormed in october with equest pramox and have been told by the YO to use this one again, this weekend.
However, just reading an old thread on here and it seems that pramox should be used regularly and my horse is at risk from colic if I use pramox, when it's been 6 months.
Also, not entirely sure of his weight and really don't want to overdose him!
My horse doesn't show symptoms of worms, in fact the other liveries have said not to bother but i'd rather be safe.
So, can anyone suggest a relatively safe wormer?

 

[CMMB]

How much of the day has he spent out over the winter, do you poo-pick the field he grazes and does he graze with other horses?
If you poo-pick regularly (minimum 1 - 2 times a week during this cold winter) I doubt very much he needs worming again until June/July unless you wanted to do him with a tape-worm only dose now. Does the yard / your vet provide a worm egg counting service?

 

[Dumbo]

He hasn't been out much over the winter at all. Probably 3/4 days a week for 1-4 hours. (Yo is very precious about the paddocks!)
Rarely poo picked. I always offer but told not to bother, however never seen anyone else do it!

Was thinking about a worm egg count. Do you have a rough idea of how much it would cost? I will look into it