The length and width of that cage is perfect the height is too much. Bearded dragon cages should not be more than 24". If you already have the cage, then I suggest using the Mercury vapor bulbs...as they push UVB much further the Tube style UVB bulbs (don't use the compact florescent tube style bulbs, they are extremely harsh on dragon's eyes...can actually damage their eyes if I recall correctly). The night glow bulb, i wouldn't even bother with at all. If you need supplementary heat at night, use a ceramic heat emitter. Keep in mind that dragon's do need a night time temperature drop as well as having all lights off. (14 day/10 night is good...)
For night time temps, it is fine if the temperature drops as low as 65F..as long as it doesn't go below 60F. Should be no more than low 70sF as well, so you do need that night time drop. So standard house temperatures are fine for night time.
For day basking temps...you need them to be in the range of 95-115F. Its best to have an angled wide basking area or multiple layers so you have several different temperatures your dragon can use to bask in, instead of just a single one. Also if you are going to try and house two dragons in that cage, then you definitely need more than one basking area so your dragons are not forced to 'stack' or compete for basking space.
There is no way to know your 90W basking bulb is going to be hot enough. It all depends on your ambient house temperatures and what sort of tank you are actually using. Glass is very poor for retaining heat, and a screen or open top, allows heat to escape quickly. Wood with a mostly solid top, or completely solid top, holds heat much better. Screen doors or side vents work best for allowing ventilation without loosing heat.
Personally, for a cage the size you have and giving the height...a 90W is not going to work at all to get the temps you need. I would try a 125 or 150W MVB and additional basking bulbs..as needed. If you are able to reduce the height of the cage, or plan to build higher levels (using ramps and wide secure basking area) you can get away with a lower wattage bulb but remember the ambient temps need to be in the mid 80's low 90's F as well..though the cool end can be in the upper 70's to low 80'sF
My suggestion is to buy a track light fixture so you can have 2-3 of the smaller flood light bulbs...so you can heat several basking areas at once...run it the width of the cage about one foot from the side wall...Most track lights you can angle the fixtures (or at least some do come in a design that allows this) this way you can adjust where the bulbs are pointing to gain a bit of control. Build or use a large wide angled or tiered basking area with plenty of room for both dragons to bask in the same temperature range at the same time, with other areas they can move to if they want to go hotter or colder. (I find dragons will bask at higher temps in the morning when they wake up and right after eating, then move to a lower basking temp once their cores reach optimal temps..then they go run around and do whatever dragons like to do when they are at an ideal temperature)
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PHLdyPayne