I honestly think that the majority of manufacturers don't provide the info. It just happened that Hydor do and they were the second I checked. I think, from memory, that I've seen the info maybe from Aqueon, but it's certainly not the easiest information to find.. and to me it can be some of the most important.Good info there doug...I actually didn't know that info was provided by the manufacturers (maybe I should read more instruction manuals) as I've been essentially basing it off of tank size myself.