200 watts sounds plenty to me. What power was the bulb that blew? It depends on the number of chicks you have, and what space they're in, but you can tell from their behaviour whether they're too hot (spreading out as far as possible from the lamp) or too cold (huddling together under it.) it's important that they have enough space to get away from the heat if they need to, as overheating can be fatal.
Is it possible to adjust the height of the lamps to increase or decrease the temperature?
When replacing the lamp, the best sort is called a dull emitter - this kind just gives out heat, not light, so it's more economical and also gets them used to sleeping in darkness at night instead of 24- hour stimulation under a bright light. See
https://www.chicken-house.co.uk/acatalog/Dull_Emitter_Heater_bulbs.html for examples
Or invest in an Ecoglow, which is an electric chick brooder, that is, an infra red heated pad, supported on legs for them to get under when they need to, like under a hen's wings. Very economical and totally safe.
http://www.brinsea.co.uk/index.php?route=product/product&product_id=587