I appreciate the support folks. Since my last post I have taken the glass covers off of the tank to help it stay cooler. I really suspect poor oxygen levels in the tank are causing the fish deaths (thank God not the Discus) and perhaps even the cause of the BBA. I kind of beat you to the punch Tom (but it is reassuring to hear you recommend this) and have increased the surface movement by pointing the spraybars up toward the surface such that there is a rippling effect on the surface. This didn't seem enough though based on looking at the fish so I have also installed an air stone in both corners. They emit a fine mist and seem to really make a difference at least looking at the fish. This morning I increased the bubble rate to-you called it Tom- 2bps..and I was pleasantly surprised to see pearling plants when I got home from work today.
PH was at 6.4 just before the lights went out. Seemed a bit low so I measured the KH and it was at 3 degrees. What's odd was that it is usually 4. Tested again and got 3. Checked the tap and it was also 3 so it seems that the tap water has gotten softer. I think that when I was using the PH controller it wasn't' delivering enough C02 because the PH setting was assuming a KH of 4, but when it went to 3 then I didn't have enough C02. This was probably happening for weeks and I didn't even realize that my CO2 levels were fluctuating because the PH was on target.
I think without using this controller and just a bubble rate like I'm doing now it won't matter if the KH Fluctuates right? At any rate the true test will be no more BBA. A little more is growing back, but I think that now I've gotten the plants pearling and have good C02 delivery it days are numbered.