with regards the lighting, i wouldnt worry too much about the spectrum, 2 x 39w also doesnt seem excessive on a 250l tank, but you could try going back to basics and removing the reflectors to help ensure good c02 availability.....that way any fert limitations will also be minimised due to slower growth and resultant reduced demands. Algae also indicates a high light issue compared with c02 availability....it sounds stupid, but even your light coloured substrate (of which there is still quite a lot uncovered) may be exaggerating your lighting by reflecting light back into the tank rather than absorbing it like darker ones.....i think im right in saying that....but dont quote me How do you dose your fertilisers, all in one dose or do you split it into daily doses? I always found i had to at least double dose (daily doses) with the old tropica tpn+, so maybe these new ferts are the same and there is still a shortfall with your current set up....although you stated above that there are no particular deficiencies so maybe this is less likely the issue.....its most likely a light and c02 relationship. I see you have moved away from spraybar configuration, is there a reason for this? Cheerio, Ady