C02 Regulator Problems - Need Advice

[Blue Ram]

Anyone using the AquariumPlants.com regulator?? I have been using this regulator with a 10 pound tank since September 06 and have had no issues. I have not had to touch the system. I had the pressure set at 5 (I assume this is pounds) and was using about 2 bubbles a second. Over the past five days, I have either been getting no C02 (it actually stopped) or too much C02. When I spoke with a rep from Aquarium Plants, he indicated that they are finding the regulator needs to be set closer to 10. I adjusted my system to 8 and was able to get the C02 running again. However, the regulator is connected to a selenoid which turns off the C02 with the lights. The past couple of days, even when the system turns off, the C02 continues to flow (about a bubble every 5 seconds). Has anyone had these problems?? The tank is 75 gal and the C02 and lights run for approx 12 hours.

Another issue I wanted some advice on is whether to run the C02 continuously so I do not have ph swings. When I test the ph in the tank in the morning before the C02 starts, it is 7.6 (typical of Calgary water). When I test it in the evening after it has run all day, it measures approx 6.6. The fish (mostly rainbows & cories) do not seem affected by this but I don't think it is the best scenario for them. Is it better to run less C02 for a continuous period??

[algae farmer]

1. Seems that the solenoid is not shutting off the flow completely. But at 1 bubble/5sec. is not a problem.

2. Your ph swing seems rather large. I run my CO2 the same as yours and I get somwhere between .3 and .4

diff.

3. How much surface agitation do you have, if any? This could acount for the large ph swing.

4. Running your CO2 for longer than the photoperiod is just a waste of CO2

[jvision]

I agree on all points with AF. IMO and IME, pH is not that big of a deal - only when it's connected with fluctuations in conductivity (like when using different salts to change pH).