DIY CO2

[TestPilot]

I'm not sure if this has been posted before, but you can build yourself a nice bottled CO2 injection system for under $130 (not including tank/gas) and never make a trip to "the store". Most of the parts can be found online from an aquarium supply store. If anyone is interested I'll write something up.

ETA: Forgot to add, if you have the $$ you can replicate the CAP monitor as it is just a repackaged GE unit.

[faithlessxxx]

I'm all ears.

[TheGreenFog]

Hey, Test Pilot. Do you have proof that your DIY system works (i.e. improves yield). What I mean is did you run a comparison test with two rooms growing side-by-side? I'm sure that's really never been done because anyone setting up a DIY system probably doesn't have the resources to run such a test. Anyway, reason I ask this is that it is debateable whether DIY systems are worth the hassle...and at $130, I personally would spring for the full kit for a little more.


I'm all ears.

You must have a huge problem with wind resistance.

[attachment=o143502]

hehe


The Fog :rastasmoke;

[TestPilot]

Hydrofarm has a good guide on the details of CO2 injection (Hydrofarm - Carbon Dioxide Enrichment Methods (http://www.hydrofarm.com/articles/co2_enrichment.php). This is mainly a guide to replicate their system using off-the-shelf parts.

For bottled CO2 injection you'll need:

1. Tank - Usually rented when you get it filled
2. Regulator - Make sure the regulator output is within the working range of your flowmeter and solenoid.
3. Solenoid
4. Flowmeter -You can use one calibrated for air rather than CO2**
5. Short Cycle Timer/Monitor
6. CO2 Tubing
7. Teflon tape
8. hex nipples (male/male)
9. barbed/pressure fitting - For flowmeter->tubing connection

************************************************** **
**If you cannot find an inexpensive flowmeter with direct read scales for CO2, you can use one calibrated for air with a conversion equation:

Q2 = Q1 * sqrt(1/1.5189)

Q1 = Observed flowmeter reading
Q2 = Actual flow corrected for specific gravity
1 = Specific gravity of air
1.5189 = Specific gravity of CO2
************************************************** **

You will connect the regulator output to the solenoid, which feeds the flowmeter which feeds the distribution tubing. (Pictures are worth 1000 words). The solenoid cord plugs into the timer.

The general idea is pretty straightforward. Figure out how many cubic feet of CO2 you need to add to raise the CO2 concentration from atmospheric (200ppm) to an arbitrary concentration (for our purposes, 1500ppm). Hydrofarm has already done the hard math and you can get it from the link. For the impatient, here's a summary (Substitute your own values accordingly.):

Release Interval: 2 hours
Atmospheric Concentration: 200ppm
Desired Concentration: 1500ppm
Raise concentration by: 1500ppm - 200ppm = 1300ppm
Room Volume: 8x8x8 = 512 ft^3
1300ppm in 512 ft^3 = "1300 millionths of 512" or .0013 * 512 = .66 cu. ft.
So you need to release 0.66 cubic feet once every two hours.

At this point you need to set your timer and flowmeter to a combination that will release 0.66 cubic feet every two hours. Ideally you'll run the solenoid for as short of a time as possible, but this depends on the resolution of your timer and its shortest possible "on-time". You will need to correlate your flowmeter range to the resolution of your timer and the size of your room.

To find the flowmeter range you need take the resolution of your timer (say 30 minute increments) and figure out what flow would be required to reach .66 cu. ft. in 30 minutes. In this case it is 1.32 CFH. (.66 CFH for an hour would give you .66CF. For half an hour, double the rate)

If you have $$ and time, the C.A.P. CO2 monitors are rebranded GE Telaire units. The "portable" monitors that G.A.C sells are also GE.

This isn't very organized. It's mainly just thoughts/notes from my own experience that may help others out. Maybe I'll come back and clean this up and turn it into a proper guide. I think the key points are in sourcing the proper parts and doing the math for flow rate.

[TestPilot]

Hey, Test Pilot. Do you have proof that your DIY system works (i.e. improves yield). What I mean is did you run a comparison test with two rooms growing side-by-side? I'm sure that's really never been done because anyone setting up a DIY system probably doesn't have the resources to run such a test. Anyway, reason I ask this is that it is debateable whether DIY systems are worth the hassle...and at $130, I personally would spring for the full kit for a little more.



You must have a huge problem with wind resistance.

[attachment=o143502]

hehe


The Fog :rastasmoke;



TheGreenFog, I don't consider this "my system" at all. It's more along the lines of some notes I think may be helpful to others that would like something similar (very very similar) to the Hydrofarm setup.

Basically, in my experiences of building a system there were a few major hurdles that I think are common to most people and these are just my solutions:

1. How the system is actually connected and the purpose of each part
2. Rate/Timing calculations
3. Finding a flowmeter/reg/solenoid for CO2
4. Sizing the flowmeter for your area
5. Finding a suitable electronic monitor from a non-hydro company
6. Lack of good product information (safe working ranges for each piece, fitting sizes, etc..)
7. Doing all of the above without any contact with a "store"

I'm a little tired, I forgot to add about the flowmeter sizing...this is for determining which flowmeter to buy. You generally have a choice of a number of ranges (i.e. 1-10 SCFH, 2-20 SCFH, 0.5-5 SCFH). You want one where the range includes the necessary flowrate you already calculated. So, say for our 1.32 CFH, a 0.5-5 CFH range would be appropriate. Also make sure the range is not _too_ large as accuracy will suffer.

[Arcamax]

TestPilot,

The milwaukee setup uses psi and KG/CM2 to show flow. I have located a regulator that lists output in Cu.Ft./Hr

What would an outflow of 15 Cu.Ft./Hr read on the Milwaukee meter?

Tia

Arc

[TestPilot]

I'm not sure what kg/cm2 you're talking about...that is a unit of pressure, not flow. The regulator will read output pressure (and tank pressure on a dual gauge) in PSI and kg/cm2. I can tell you that the milwaukee gauge reads in PSI.

The flow meter will read in CFH, CFM, etc...

You need a regulator, flowmeter and solenoid valve.

At 15 CFH in an average size room I would guess you're dosing 1-2 minutes at a time?