Plants suddenly dying in strange pattern
So my ammania sp bonsai suddenly started to die. But they die as if they are catching a disease and spreading it. First the plants on teh right turned brown, now they are mush. Then the plants to their left turned brown. Then the plant closest to that turned brown. Until they start quickly turning brown, they are completely green. I have others in the tank that are very green. This has happened over the course of only 2 days
Has anyone seen this before. Should I removed these "diseased" plants?
I use Eco complete substrate with sand cap/mix. I dose half mL of excel every 3 days (10 gallon) trying to go slow and flourish every other week little less than half mL. The tank is cycling and I had done water changes to bring nitrites/nitrates down, which were very,very high. They are still high but now at least nitrate readable. But for this, I still don't understand why they don't all melt at once. I use lights 9 - 9.5 hours 2 13 watt CFL. Low for this plant maybe but am not convinced it would make plant die this way