Soil based natural planted tank setup 3.5 weeks ago and having algae problems. One problem I see since this is a soil based system-is that you don't have enough stem plants to help with nutrient overload from the soil. Do you know what kind of algae-I assume these are new bulbs and while they are within the color temp range at 5100k-I have found 6500k to work better.
With planted tanks and problem algae-usually it will be light and nutrient related-especially on a new setup. Its all about balance-the plants have to out compete the algae. While some species of algae is normal, expected and a sign of a healthy system-when it starts to be problematic this early on setup-You system is out of balance. Could be due to lights and ferts without enough of the right species of plants and good plant growth to out compete the algae.
Is this an open top or do you have a partition between the lights and water-how far are the lights from the water. Especially with hair algae-if the partition is dirty or light too close to the water can be a cause of hair algae.
What I would recommend-add more stem plants-naja grass would be a good one to use. Stop all ferts-you don't need it with the nutrient rich substrate and this could be feeding the algae. Make 50% water only change for 2 days-If you can-find a couple of 6500k bulbs and increase your photoperiod to 10h/day. Then do 50% water Only twice a week for the next 2 weeks. Try not to disturb the substrate at all and allow some of mulm/debris to break down so the decomp can add some natural CO2.
I've done the water changes as suggested and did clear up nicely for a while. I have several anubias, java fern, naja grass, and duckweed being sent my way too which should help. The students have been learning constantly which is nice; but I'll admit, even I have learned some interesting new variables along the way.