Hi Rudi and welcome to MASA.
The lighting upgrade choices on your Boyu TL450 are unfortunately very limited.
At best you can add another 18W PC tube to the existing hood, but even this can turn out to be more effort than what it is worth.
To do this , you need to remove the hood and the 2 x 18W PC's. If you move the mounting brackets for both of the existing PC's slightly outwards , it should give you enough space to insert another PC tube in the middle. Just remember you will need to also add another ballast , which will increase the heat build up in the existing hood.
Depending on the outside temperature , this additional heat build up could increase your water temperature , so keep an eye on this.
IMO, I would get rid of the existing hood and rather look at adding a couple of T5 tubes . You can either suspend the T5 pendant above the tank or alternatively create a mounting bracket which sits on the tank. Just a note though ; The T5's are approx 490mm in length , so you will need to mount them diagonally over the tank. Otherwise , you will find that the T5's will stick out on both sides of the tank.
Hope that makes sense.
I've gone with a 70W MH fitting and DIY'ed a canopy for my TL450.
May sound extreme , but it works great !
