Luckily I haven't had it happen, but hopefully with the needle valve it wont or at least be minor and not nuke the fish. I have to 5lb tanks so when I see the active tank running on the low side I just switch it out. However I did have a cylinder empty in one of my tanks when I was in Cuba in December. Still don't know what the hell happened. Was reading half full when I left, I came back and the tank was empty. No casualties, so I guess the dump was minor. Bless those needle valves! I probably just jinxed myself......

Tom, you frequently mention that PH controllers are a waste and shouldn't be relied on. I'm on the fense. I have one and for most practical purposes it works. What are some of the common F ups that using a controler sets you up for? I don't blast my CO2 with an open valve and put total faith in the controller. Reason being is that I feel I can get more mileage out of my solenoid just having it turn off and on once daily, unless my PH gets under 6.5 and the controller shuts it down. I don't count the bubbles either, I just get my CO2 up to 35ppm. My PH swing is roughly .5-.6 from morning to evening. Should I continue with it's use, and if so, am I setting myself up for possible disaster.

Cheers.

Zig.