Let me see if I can explain. Sometimes we do talk about watts per gallon, but it truly is a lousy rule of thumb really. There are other factors involved like depth of tank, intensity of light (not the light you see but the PAR value).
We have/had a member here with a sebae and kept it under 260 watts of PC lighting in a 75 gallon tank, it was white when he got it. After months it started to regain its color back but not very well. With this lighting he was at 3.71 watts per gallon.
He then upgraded lighting to 440 VHO and 500MH for a total of 940 watts on a 75 giving him 12.53 watts per gallon, and the sebae regained its zooxanthellae within 5 months (see thread below)
Now most sebae's will place there foot in the sand right near a rock, so its at the bottom of the tank, here is where that par value comes into play, the lighting will have to have punch all the way down to the bottom of the tank with useful lighting. As most VHO and PC lighting will start to diminish its useful light 12 to 16 inches down. Yeah I know you have a 25 gallon therefore its shallow, and I can't predict your success with the lighting you have but I can show you the difference between "surviving and thriving"
Take a look at the following thread where broomer5 talks about his sebae on page 2.
https://www.saltwaterfish.com/vb/show...e&pagenumber=2
