Cheap DIY Hi-Tech CO2 injection method
[Author's note: The following article was first posted to sg.rec.aquaria newsgroup on 30th October 1996]
Currently after much evaluation of Dupla's and a host of other commercial
brand of CO2 setup, they are either overpriced or of inferior quality.
So I decided to put my creative talent to good use by building a Hi-tech
CO2 setup myself.
I use a semi-automated CO2 injection system that I put together to provide
the proper levels of CO2 for optimum plant growth and stable pH in my
plant tank. The CO2 system is fed from a 5 litre CO2 bottle with a
commercial two stage regulator, thru a solenoid valve and fine control
needle valve into the bubble counter before being discharged by a CO2
reactor. All available from local Singapore sources.
Here is what is recommended you should get:
CO2 cylinder & Solenoid valve
I got mine from a commercial gas company, it carries all kind of cylinders.
Like I mentioned, a 5 litre one will do and it will definately outlast any of
the range of CO2 bottles carried by Aquarium supplier. A simple reason is
that they want you to go back and refill all the time, more business.
But as for a single 5 litre refill, it will probably last you a good 9
months if the bubble goes at a rate of 1 bubble per second. The place
where you buy the tank should be able to refill it.
Get a 5 litre CO2 tank from :
Sing Swee Bee Enterprise Pte Ltd
Tel : 7527892
* Important thing here when getting a refill, ask for the type of CO2 that
is food grade suitable for human consumption. Most of the aquarium shop
don't even know the difference between a food grade CO2 and an industrial
grade CO2 (which is useless for Aquaria, industrial grade CO2 feeds all
kind of mixed gas besides the C02 that bubble into the atmosphere and
poison your fish and plant, not excluding yourself! hehehe:)
Regulator
Next thing you will definately need is a regulator, the place you bought
the gas tank from also sells regulator. The best is a two-stage regulator
designed for use on welding gas cylinders. This reduces the 950 psi tank
pressure to 10-20 psi. The regulator has high and low pressure gauges and
a control to set the low pressure. I set the low pressure to be between 2
and 4 psi to allow fine adjustments of the actual flow.
You can get a high quality stainless steel twin gauge one that beats all
the commercial ones sold by the aquarium shop hands down! And the beauty
of it, you pay less for more, for just about S$70.00 dollars, it is a
lifetime investment that won't break down. I paid $70 for an adjustable
regulator with high and low pressure gauges.
The high pressure gauge tells you when the bottle is about empty. The
bottle pressure will stay at 950 psi as long as there is liquid CO2 in the
bottle. Once the liquid is gone, the pressure will begin to drop. When the
pressure is around 200 psi, you should recharge the bottle since the
regulator gets a little flaky at that point.
You can also get the regulator from the same company
: Sing Swee Bee Enterprise Pte Ltd
Solenoid controller
For automated time release of CO2 is a solenoid device capable of
controlling up to 100 psi. My solenoid is controlled by a light timer set
on regular interval. It can also be controlled by a electronic pH
controller if you want to get fancy. I found a commercial unit for about
S$60. It's definitely over-kill but it has never broken (Made in USA, damn
good stuff!). It's good for 200 psi and it's non-corrosive.
You can get it from :
Beaver Contromatic
Tel : 7469677
Model : 21A2kV30
Type : 240 VDC
Cost : S$60.00
The solenoid goes after the regulator on a CO2 cylinder, i.e. the low
pressure side. Some solenoids use the inlet pressure to help keep them off
and may not work in this application.
The regulator usually has a 3/8" NPT thread and the solenoid may have a
1/4" or 1/8" NPT thread, so you will need to find a place that sells step
up and
down thread adapters. Most good hardware stores and plumbing supply
places have these. I found a good source where you can get all sorts of
valve and adapter, at a company called : Singapore Valves & Fitting
Fine adjustment control
After the regulator, you will need a fine control valve to regulate the
flow to get the extremely slow flow rate you need (1 bubble per second for
a manual setup). I have a Nupro needle valve to provide the final flow
adjustment into the reactor. With the low pressure, the valve can easily
be set to a flow of 1 bubble every 10 seconds. Initially, we have it set
for 1 bubble every 1.5 seconds. It is a pretty Hi tech stuff for
industrial use which you could get for $60. Typical aquarium needle
valves won't work - you will find they are either all on or
all off in this application.
I have one by NuPro (model B-4MG2) that cost S$60.85 and is superb, state
of the art stuff. Another worth-every-penny-investment.
You can get it from :
Singapore Valve & fitting Pte Ltd
Tel : 3670688
Model : B-SS4-A/ Nupro Fine metering valve
Type : Brass
Cost : S$60.85
Bubble counter
To help set the flow you would need a "bubble counter" to provide a
visual indication of the actual CO2 flow. You can inject directly into the
tank or you can see how much is going into the reactor, this is optional.
I made a homemade Bubble Counter (from a mini baby milk bottle which you
can buy it for less than $3, comes with a silicone nipple on the
inner cap)
I drilled 2 holes top and bottom and fit in a single 1/8" plastic valve you
can get at any aquarium shop for S$0.15 and silicone it to seal off the
gaps, fill it up 3/4 with water and that's it, a bubble counter. The cost
of it, for less than $4 bucks and I provide a check valve to prevent water
from backing up into the solenoid and regulator (something to be
avoided!).
Silicone tube
I was ripped off when I bought some silicone tube. I went to "Aquatechnique"
and the salesman sold me 3 metres of silicone tubing by Dupla for $7.50 !
and later I found out that I could get it for $0.50 per metre at the local
aquarium that carry silicone tube!
I have a three-millimeter or 1/8 inch thick silicone tubing that is used to
connect the bubble counter to the valve and reactor. The bubble counter is
mounted on the front of the trickle filter so it is easy to monitor.
CO2 Reactor
It doesn't have to cost you an arm and a leg to build a reactor and the last
thing you would want is to get a dupla reactor from Aquatechnic, it cost a
mini fortune. Anyway, lots of dump folks got ripped off by them. I built my
reactor fashioned out of a 200ml baby milk bottle which uses a very high
grade polycarbonate plastic. It works great as it comes with a silicone
nipple which can act as a watertight seal. Drill 2 holes on the top and
bottom and glue in a single plastic gang valve from the bottom for the
silicone inlet tube. the top one is fitted with an elbow adaptor that goes
into my canister filter. The CO2 gets pretty much chopped up by the time
the water enters into my tank. Throw in a couple of mini bioballs into the
cylinder and voila! you have a reactor for less than $12 bucks! You can
use your imagination to design all kind of reactors that will work for a
song, only if you put in some time.
So here's a rundown of the parts and cost of my typical CO2 system:
5 litre CO2 Tank - S$85.00
CO2 regulator - $75.00
Both bought at :
Sing Swee Bee Enterprise Pte Ltd
Tel : 7527892
Solenoid controller - $60.00
Beaver Contromatic
Tel : 7469677
Model : 21A2kV30
Type : 240 VDC
Cost : S$60.00
Nupro 'S' series metering valve (needle valve)
From : Singapore Valve & fitting Pte Ltd
Tel : 3670688
Model : B-SS4-A/ Nupro Fine metering valve
Type : Brass
Cost : S$60.85
CO2-approved airline tubing - silicone ones are also good. Don't use cheap
aquarium airline hoses, they may become brittle and leak under long-term
CO2 exposure.
3m - $1.50
Available at all aquarium shop
Total cost for a Hi-tech CO2 injection : SGD$282.35
Not too bad for a hi-tech CO2 injection system if you look at long term
cost of less than $5/- per month if you use it for 5 years. Really
worth the hassle!
You don't have to be rich to be clever - Ikea
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