had an epiphany moment this morning while in the shower ... like you do. all my T5 lighting is compact, therefore only 21" long (i was offered a cheap unit)... so, my effective 110watts, is squashed into only about 2/3rds of the tank.. that makes my wpg about 4 over that area no wonder im fighting algae issues.. this also explains why my hygrophilla's are so nutrient thirsty at the moment, and show signs of faltering after only 2 days of a deficiency (i ran out of NO3).. theyre being driven at about 200% the rate i want them to be. think it might be time for an early christmas present and get a full length luminaire. this also proves that all EI scheduling calculations are very much dependent on the amount of light you have... so if your running more light than the average (we wont know what figure Tom Barr tested EI on) then you need to increase your dosing accordingly. this is obvious I know, but worth pointing out.