Join Date: Mar 2019
Location: Edmonton, AB, Canada
Could you clarify if the tank is one week old, or if the new plants you purchased are one week old? Any livestock in the tank?
I've always thought that plants need some time to root themselves before they really start using up the nutrients and light that we give them. Might be worth checking your water parameters (if you haven't already) to see where you're at and adjust accordingly. When a tank is new, I don't think it's beneficial to saturate with ferts and light. Start by reducing both, and perform some sequential water changes removing as much physical algae as you can. Then test again and dose as needed. Maybe start at 50% light, or a shorter lighting period. Once the plants take hold, you can start to ramp up your lights and ferts. Daily water tests can be a good indicator of how much the plants are consuming.
*Disclaimer: I'm also relatively new to the hobby, and have also had a rough start with algae. Hope this information is correct and helpful. :P