In my gym (the new one) they have Atlas Lighting 400 watt Metal Halide fixtures. When first turned on, they give off a REALLY BRIGHT looking incandescent light for a few seconds. Then the lamp strikes and it fires up normally. What causes this? The ignitor?

This is normal. What happens is that when the fixtures is first turned on a halogen lamp (usually 500w) comes on before the main light fires up. It serves another purpose. If the power is interrupted the halogen lamp comes on while the MH cools down before re-striking again. They're called stand-by lamps.

I have seen a few areas using those stand-by lamps:
Brazil (I used to have a pic of the light. My computer's HDD bit the bullet so I lost the files. )
High-bay (It's on.)
Recessed (Below the lamp.)
Parking lot light (Upper right of the pic. (Missing cuz the merc lamp is reliable. Dunno why no one caught on that. )
Those things are more common than you might think. (Know of a few others that I will take a pic of them later on.)

Strange thing! While I was walking around the area exploring. I found an electrical supply store. (100% electrical) The stores sells HID fixtures of all kinds. (No cobrahead or NEMA.) Even sells ballast kits, (Didn't check the price.) The brand I found there is also Atlas Lighting. (It's true!)

I usually fire these up in the morning when i go. (i know the people there real well)  Would it do this if i hot restriked them?

Also, do they make color corrected mercs that are clear? This is another issue with another gym i know about. The breaker says 1000 watt Mercury Vapor highbays, but some of the lamps are clear and some coated (the newer ones clear) and you would think color corrected mercs would be coated.

You never tried turning them off after they warmed up and turned them back on and watched them come on one at a time? No harm in doing that once. Yeah they're supposed to do that (halogen lamps fires up while mhs cools down.)

(It's cool to watch them come on after power interruption one at a time. (Happened at a gas station during an ugly t-storm during vacation. Somewhere in VA I think.)

You bet if I ever get a chance with them again I would turn the lights off then back on and filmed the show. (Make the film 3X faster than normal if it takes too long.) Only have to keep an eye on my back for security or staff.

Do they make color corrected mercs that are clear? This is another issue with another gym i know about. The breaker says 1000 watt Mercury Vapor highbays, but some of the lamps are clear and some coated (the newer ones clear) and you would think color corrected mercs would be coated.      jace? do you might know?

The only way a mercury vapor can be color corrected is if it s coated. A clear MV will not emit red light so everything will look a weird blue-green, The phosphor coating adds the red to make the light a more normal appearance and objects don't look as 'ghostly'.

Another thing, not all MH types have ignitors, only the pulse start have the ignitors while probe start is more like what MV has and does.