heater question please help?

  is it ok to use a 200 watt heater instead of an 150 watt heater, ive just bought a 200 watt heater your advice please.
that would be fine ... your tank is about 32 us gallons and for heaters it is a ballpark of 5 watts per gallon ... so 5 x 32=160 watts ... so 200 watts is not excessive ... i have a 200 watt in a 30 gallon as well and all is fine: O)
Yes , the heater will keep the water the same temperature as a 150 but will do it faster. You would be better off using 2 heaters instead of 1, just in case something happens to 1 of them. What size tank do you have?
It is fine to use a 200w heater. the heater should be thermostatically controlled so the tank will be at the same temp as if a 150w heater was used. The wattage is just the power output of the heater. The higher the wattage the quicker the heater will heat the water.
How big is your tank? As long as you can adjust the temperature on the heater (not one that automatically raises the temp 5 ° F) you should be fine.



* Edit: The 200 will work fine, it will be more efficient than the 150 would've been.