Ok so here goes what I've done so far.
1) water changes
2) added salt
3) raised temperature
4) removed carbon and cleaned out that filter
5) added esha exit for the last two days
5) added esha 2000 the ray did not like this so discontinued.
6) have a large bottle of melafix ready for after med treatment.
Results so far. The velvet had cleared up significantly between 24 and 36 hours.
Fish are blacked out but checked them and all alive. Coming up to the 48 hour mark and only one fatality a large apple snail. Clown loach didn't do take too well acting strangely but seem ok now.