Another co2 question

red devil

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Jan 7, 2003
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I did a brief search on this question but after reading dozens of posts decided to post it anew.

I am going to build a diy co2 system and am wondering if it is possible to control the production of co2, specifically, if I can slow it down at night when plants need oxygen and give off co2 themselves. Some ways I was thinking about controlling the reactor are:

1. putting the reactor in a warm water bath with a heater on a timer. From 7 a.m. to 7 pm ever day the heater will be on, heating the water up to 90 degrees fahrenheit or more, then after that the water temp will drop to room temp.

2. putting a screw type fish food feeder (on a timer) in the reactor with enough yeast/sugar mixture to fizz for about 12 hours. For this kind of reactor I would use a rectangular box with a silicon seal and clamps to keep it shut and use a battery operated feeder.

3. Maybe even leaving the lights on 24/7 in the tank? Would this be ok for the plants/fish?

Any feedback is appreciated.
 
Of the three ideas the heater idea seems like the best bet. The only other way I can think of doing it is with some kind of diverter valve, but I have no idea what equipment you would need to set that up on a timer.

Let me ask you a question. What's wrong with keeping the CO2 on 24/7?

Just operate your lights as you normally do and make adjustments to CO2 volume by adjusting the number/size of DIY bottles you run.
 
One of my tanks I inject pressurized CO2 at 1 bubble per second, 24/7 (waiting on the solenoid). No harm to the fishes and 1bps is more CO2 than what a DIY setup can maintain. Unless you're dealing with multiple bottles, excess CO2 isn't a problem with DIY setups even at night.
 
Thanks! Yes, I was concerned with OD'ing on CO2. Actually, maybe not OD'ing but providing CO2 in the dark hours when it was not necessary. I just moved, so after a week I am going to go tank shopping. I think I will start with the most common size tank here, which looks to be about 20g.
 
One of my tanks I inject pressurized CO2 at 1 bubble per second, 24/7 (waiting on the solenoid). No harm to the fishes and 1bps is more CO2 than what a DIY setup can maintain. Unless you're dealing with multiple bottles, excess CO2 isn't a problem with DIY setups even at night.

au contraire.. i've got 2bps going to my reactor for the 75g.. one 2L bottle maintains this for approximately one week.
 
od co2 is it pushes all the o2 out of the water and they suffocate. very very hard to do in a diy setting.

Not true, you can have CO2 poisoning well before there is enough CO2 gas to displace O2. You can have high CO2 and O2 levels at the same time.

The problem lots of people have where they see fish gasping at the water surface after the lights are off isn't because of high CO2 levels, but low O2. Plants aren't generating O2 after lights out and many people reduce the surface agitation to a minimal for planted tanks, so you have little O2 going back into the water. To prevent this problem, provide adequate surface movement and circulation.
 
The problem lots of people have where they see fish gasping at the water surface after the lights are off isn't because of high CO2 levels, but low O2. Plants aren't generating O2 after lights out and many people reduce the surface agitation to a minimal for planted tanks, so you have little O2 going back into the water. To prevent this problem, provide adequate surface movement and circulation.[/QUOTE]

Yes...that is another solution, to get more O2 into the tank after the lights go off and stop producing photosynthesis...more agitation or even an air pump with a stone on a timer. It sounds like that is the easiest solution to the problem, rather than trying to control a DIY CO2 setup.
 
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