He is currently in a 20 gallon long but he will be in a 24x18x18 very soon! And what do you mean about the daylight savings! He currently had his light in from 8am to 8pm.
Sorry I confused you.
ON/OFF thermostats could shorten the life of your DHP. Dimming (proportional) thermostats don't have that risk, but are considerably more expensive!
Is there some chance you might upgrade to a 36 x 18 x 18 instead of a 24 x 18 x 18?
Even with a DHP it's important to have something like a 15 watt incandescent bulb overhead dimmed to half power during the day to establish day & night.
Keep your leo's light on from 8 am to 8 pm (daylight savings time). 11-12 hours
ON right now is excellent! Some keepers vary
light on times -- less in winter, more in summer. The Timebie links just show how daylight varies throughout the year in different countries.
I don't know whether it's better to use an 80 watt rather than a 50 watt DHP for a 24 x 18 x 18 inch enclosure. Within your 20 long: 30 x 12 x 12 there's 6 more inches to create your leo's thermal gradient. Those 6 inches may be important.
IF you kept your leo's 20 long I recommend this setup.