Does sunlight really cause algal blooms? What can I do?
I’ve just had a green water outbreak in my 90 gallon.
1/2tsp KNO3, 1/4tsp KH2PO4, Seachem Equilibrium, Flourish and Prime all go into the tank once a week with a 20% water change. Also a bit of bicarb soda to keep the pH at 6.8-7
Gluteraldehyde approximate to 1.5x Excel dosage goes in daily.
Lighting is 106w T5HO. Might seem a lot, but it’s 4” off the surface and the tank is 24” high.
Nitrate stays 10-20ppm. Don’t know about phosphate levels.
I’ve seen this exact setup work for others with no problems.
The only thing that has changed in the set-up is the fact that the seasons are changing, so much more sunlight is coming through the skylight. It falls directly on the tank for around an hour a day.
So assuming that, judging from that setup, it’s the sunlight that’s causing the green water, what can I do about this? Just turn off the lights when the sunlight strikes the tank? Reduce the photoperiod? Or do I have to board up the skylights?