I like to run the stronger HO bulb for 3-4 hours mid day to simulate the strong mid day UV spike that happens outside. I think Mark said he prefers 5 hours in a previous post here. Since you are mounting this at the right height and only using it for part of each day, the shorter bulbs should be fine.
This may be a really stupid question but what sort of fitting/control thing do I need for this? I can’t seem to order a kit online in the UK.
Thanks