Planted Tank Guru
Join Date: Sep 2006
Location: Northern California
I would prune of all the leaves affected by BBA, remove as much of it as you can. Try an Excel OD spot treatment in areas heavily affected by it. Refill your CO2, then crank it up while your fish load is still low.
Yes, you had an end-of-tank dump. A sure sign is when the pressure drops dramatically a week or so before the tank runs out, much like your situation.
And yes, a LPR most likely would've helped to alleviate this situation, if not preven it. LPRs are designed to vent any gas that exceeds a certain psi. So when the end of tank dump occurs, all the excess would've blown out the vent hole instead of going into your tank.
Sorry for your losses....but it seems as if this week has been particularly bad for CO2 disasters. I think I've read maybe 3 or 4 threads, including yours, that have to deal with gassing fish due to CO2 problems!