CO2 -- run it 24/7 or not? - Page 3 - APC Polls

imzadi · 04-20-2007, 06:08 AM

My Co2 shuts off at night, but I have mine on its own timer so it comes on about 2 hours before the lights do. My drop checker tells me that in the AM right when the lights come on that the Co2 is a little high, but it evens back out to the usual 30 ppm within an hour or two. I've found that I get a longer time of the plants "pearling" when I do this, and I'm trying to get extra growth without stressing my fish.

trenac · 04-21-2007, 03:55 PM

Since I run pressurize mine turns off with the lights.

snickle · 04-21-2007, 03:57 PM

I run pressurized and try to keep the CO2 at 15ppm. I run 24x7.

Left C · 04-24-2007, 04:46 PM

Quote:

Originally Posted by mousky

During the day when plants photosynthesize they use CO2 and emit O2 as a by-product. At night when the plants are 'asleep' they switch to a reverse photosynthesis, using O2 and emitting CO2....

Plants really use O2 24/7 for cellular respiration just like most living organisms. "reverse photosynthesis" is not a good way to describe how plants use O2. That would imply that the plants are giving off light as one of the final steps in "reverse photosynthesis." The photosynthesis cycle basically just stops in the dark. But anyhow...this is a discussion about using CO2.

deepdiver · 04-24-2007, 05:04 PM

I run it 24/7, but I would rather use a pH controller. It's just one of those things I keeping forgetting about. Maybe because of the price?

orlando · 04-24-2007, 06:14 PM

how do you run 24/7 co2 without fish fatalities. Or super low ph?

Left C · 04-24-2007, 06:17 PM

I use pH controllers.

Troy McClure · 04-27-2007, 07:54 AM

Quote:

Originally Posted by Left C

That would imply that the plants are giving off light as one of the final steps in "reverse photosynthesis."

Ha, now would -that- be cool!

I have solenoids time with the lights on three of my tanks, and one tank that has a ph controller because I only see the tank once every week or two. Can I vote twice?

There's no need to run CO2 at night so if you can shut it off, why wouldn't you? I plan on running airstones at night on a couple of the tanks to see how it goes. An hour after lights out to an hour before lights on should be more than enough. Anybody know of some good deals on 3-prong timers?

snickle · 04-27-2007, 02:44 PM

I now run my 24x7 at a daylight target of 15ppm. My dropper checker stays a constant color, but of course they are slow to react.

furballi · 05-08-2007, 06:57 AM

Quote:

Originally Posted by bpimm

After switching to a drop checker to monitor CO2 levels I have noticed that when running the CO2 24/7 the reading is the same 24/7 there is no change from lights out to lights on. My theory is that the plants use and produce such a small amount of CO2 compared to the amount we put into the tanks that it doesnt actually change the overall CO2 level in the tank. the out gassing of CO2 into the air is by far the largest user of CO2.

Any thoughts

Brian

You are correct. Using calibrated lab equipment, the CO2 level in my 50 gal tank is 15 ppm (light ON/filter ON/CO2 ON) and 3 ppm (light OFF/filter OFF/CO2 OFF). Under normal condition, the CO2 range is 15-16 ppm with 24/7 injection. And no, I don't have duckweed or a sealed top aquarium. The CO2 level will fluctuate after a 50% water change, but that should be expected with the use of tap water.

Plants don't need 30 to 50 ppm CO2 to achieve healthy growth. If you want to save $ on CO2, then invest in an efficient reactor chamber and maintain the CO2 level at 15 ppm (equivalent to terrestial environment). A very light current in the tank is sufficient to keep any aquatic plant in top condition.

KISS. 24/7 may cost a few extra bucks of CO2 per year, but you'll sleep better at night knowing that your CO2 injection rig is almost idiot-proof. Remember that a timer to control the solenoid will also consume electricity (2 watts nominal). The solenoid assembly will also draw 3 watts for 8 hours per day. The nominal cost of a KWH in the US is 15 cents including taxes and misc fees. The annual cost of electricity to run the CO2 solenoid is approximately $3.94.

I paid $6 to fill a 5 lb tank which is good for 18 months. The average fill-up cost in the US is $10. With the use of a solenoid, you may be able to save 70% of the CO2 ($7), but you'll have to pay an extra $4 in electricity. I don't sweat over $3 worth of pocket changes.

If you account for the initial cost of equipment, then the pay-back period for a solenoid rig will approach ten years. A basic quality regulator/needle valve assembly will cost $75 ($55 bucks if you local Fabco distributor is willing to provide a sample of the NV55 needle valve). The average cost of a CO2 injection rig with solenoid control is $110. When you factor in the annual savings of $3 in CO2, it would take 12 years to recover the higher initial cost of the CO2 injection rig.

BTW, many industrial-grade magnetic solenoid relays will require cleaning/replacement after 10 years of normal use.