Yup, except in circumstances where it's only can be a little water - I put valves. Turn the valve, unscrew the union ... only minimal water from in the plumbing itself.
There's also something called a `true union ball valve' that is a ball valve with a union on each side ... so you can unhook either side of the valve [as a union]. Not at all cheap, though.
Great questions, you won't regret starting to learn before you get things rolling.
What do the bulbs look like on the setup? The bulbs themselves can tell you the difference:
Once you know the type [ask the wattage too] then you can ask the specific `can I keep what I'm looking to with these?' question
VHO - look quite similar to standard flourescents, straight, maybe 1.5" around.
Power Compact - bulbs are always in an extended `U' shape. Like this
May or may not have a reflector.
T-5 look similar to standard flourescent `tube' bulbs [like VHO] ... but these are about as big around as a nickel. Thin bulbs like a PC - but where PC is always the `U' shape with the complete sprocket on one end - VHO/T-5 have sprockets on both ends. Bulb size between PC + T-5 isn't much different, shape completely.
Will generally have a reflector, a better one than you'd see for PC or VHO - often can be for each bulb.
Metal Halide - There are two varieties, both are in a reflector most often.
`Single Ended'/SE/Mogul
Has one screw-in base - other end of bulb is not attached to anything. Some have behind glass, but many run these without any acrylic/glass `shielding' between it + water.
If you see one that's not in a reflector - this will likely be it.
`Double Ended'/DE/`hqi'
Fits into a holder similar to a halogen lamp - held at both ends. Smaller bulbs, often incorporating an efficient reflector design -- always with UV-shielding glass below. [read well on this before running this before running any without a shield]
That's the basic bulb types, so you can ID what you're looking at.
Have you seen waterkeeper's thread on lighting?
What are you looking to keep in your tank?
What are you going for?
I guess those are my additional questions ...
Good lord ... `sprockets' :lmao: