We were out of town for a couple of days and just came back today to find out that the water in the fish tank is nearly black as if filtration has not been working for days! All fish are at the surface grasping for air. Growbed water level is two inches above gravel. Many of the leaves of the long beans are yellow. Tomato plants are nearly dead.
I think for some reason the outflow from the growbed reduced and that increased water level in the growbed. Having water level above gravel caused incoming water to bypass the gravel and return back to the tank without filtration.
For now I have increased waterflow from the pump, removed the pipe that maintains water level in the growbed and did a couple of things to speed up returning waterflow.
Growbed water level is now normal, but I hope all fish and most of the plants will survive. 😦 Will wait and see.