UVS not working on green water

• pH: 6.8
• Temp:
• KH: 7
• GH: 12
• NH4:
• NO2:
• NO3:
• PO4:
• Iron:
• Dosing: 30 mL Excel, 1 tsp MgSO4, 2 tsp CaSO4, 18.75 ppm NO3, 2.4 ppm PO4
• NO3:PO4 Cumulative Dosing Ratio: 7.8

Notes:
50% water change:
2 tsp baking soda
20 ml Amquel+
2 tsp CaSO4
1 (heaping) tsp MgSO4
30 ml Excel
18.75 ppm NO3
2.4 ppm PO4

Even though I added less baking soda (2 instead of 2.5 tsp), the KH is still 7, instead of the target of 5. I've also upped the

Two weeks ago, I cleaned the cannister filter, and it seemed to help the UV sterilizer in the beginning of the week, but the green water is still persisting. After a couple weeks, it doesn't seem like the UVS is making a difference.

I didn't have a chance to do a water change last week, and I noticed green hair algae growing on the plants this week, with some sort of slight nutrient deficiency in the L. repens and the glosso (yellowing of leaves). I upped the magnesium a little bit for this water change.