So, i've been trying to figure out everything all at once leading to not having anything figured out. Allright Mike, focus ...
My lights! The precious owner went somewhat all out for a simple juwel tank and upgraded to Sera led tubes replacing the original t5 tubes.
One is a daylight tube, 6000 to 8000 kelvin, 1103 lm, 45 watts.
The other is a sunrise tube, 3000 to 4000 kelvin, 320 lm, 45 watts.
So in full song, they put out 90 watts, making for 0,5watts per liter in my 180 liter tank. So, this expensive setup gives me what is pretty much qualified as low lighting, which is ideal for my low tech setup i guess, so i'll run them at 100%!