BEFORE YOU START:

CO2 tubing is rigid compared to airline tubing and does not slip on and off as easily. This is necessary in order to maintain pressure in the system. To make it easier to hook up your tubing "circuit", dip the end of the tube you want to connect in a glass of hot water for a few seconds to soften it and dip the other side in water to lubricate the connection. If the connection is made properly, once the water dries, it should be very hard to pull the tubing off. If you need to remove the tubing from something delicate - the stem of the diffuser for eg. - slit the tubing open with an sharp art knife or razor blade rather than forcing it and potentially damaging your equipment. 

You will also need to soak your diffuser in warm water for at least 6 hours or overnight. Afterwards, you will want to make sure that there is water inside the diffuser body so that the bubble counter will work. If there is no water in the diffuser, unscrew the top of the diffuser, fill it with water most of the way and screw it tight again. You'll be relying on this to guage the rate of CO2 injection.

PART 1: POSITION YOUR DIFFUSER

Pick a spot to place your diffuser: Keep in mind that you want to either spread the CO2 micro bubbles throughout your aquarium as much as possible or dissolve them as much as possible into the water column so you want to place it somewhere that catches the natural current in your tank created by your filter and/or powerheads. You may need to experiment after the CO2 has be connected to find the best spot so keep in mind that you may have to move the diffuser later so don't superglue it to the glass...

If you have a canister filter and an outflow aimed at the opposite side of the tank (such as a Lily pipe) - we suggest placing your diffuser on the opposite side of the aquarium from the outflow where there should be a down current which will carry the bubbles all the way around the tank.

Alternatively, you can also place the diffuser under a powerhead intake which will spray the CO2 bubbles throughout your tank. This is probably the most efficient way to fertilize with CO2. You can use a very small (4 watt or less) pump if you do not want too much water movement.

Placing your diffuser under a filter intake so that the CO2 bubbles are pulled into your filter can be a good solution. Your filter will act like a reactor and dissolve most of the CO2 completely into the water so there are few to no visible bubbles. This results in a high level of dissolved CO2 in your water column. Be sure that you have some water circulation in the tank and watch out for "dead spots" caused by hardscape or overly dense plant growth. 

Once you've selected where you will the initially placing your diffuser, attach the tubing to the end of the stem using the hot water method. You only need a 1/2" or 1.5cm overlap for a secure connection.  Stick the diffuser to the wall of the tank with the included suction cup and hang the tubing out of the tank. Keep in mind that you may have to fine-tune its positioning after the CO2 starts flowing.

PART 2: MOUNT THE REGULATOR

1. Remove the protective cap from the SodaStream canister and ensure that the mount is in good condition.

2. Ensure that the SodaStream adapter is already pre-installed and on tight as tight as possible with your hands.

3. Screw the SodaStream bottle onto the regulator with the adapter. You should be able to do this by hand using the body of the regulator as a grip. You will hear a chirp sound or a hiss when the regulator has engaged the pin and the seal is tight. The needle on the pressure guage should move up slightly as well - showing a working pressure of around 25-30 psi

There should not be a prolonged release of CO2 - if there is, completely remove the regulator as quickly as possible and try again, being extra careful not to crossthread.

PART 3: CONNECT REGULATOR TO DIFFUSER

If you've figured out where you will be placing your regulator and SodaStream canister, cut the tubing at an appropriate length. It's a good idea to keep the tubing circuit as short as possible that you are still able to move the regulator or diffuser freely without pulling on the other end. 

Once you've measured out the amount of tubing you want, cut it. Then go back the diffuser end and cut the tubing 10" from where it meets the rim of the tank. 

Connect the severed section to your regulator. Unscrew the retaining nut over the gas outlet and pop the tubing on, the tighten the nut back to keep it secure.

Blow on one end of your checkvalve to see which way it flows and use it to connect the two ends of your circuit so that gas can flow toward the diffuser but not the other way around. Use one hand to hold the tubing in place when you tighten the retaining nut so that it does not twist the tubing too much.

When you are done, there should be an uninterruped one-way "circuit" going from your regulator to the diffuser.

PART 4: ADJUST YOUR FLOW RATE AND FINE TUNE DIFFUSER POSITION

With the gas source and diffuser connected - you're ready to go. Before you start however, make sure the needle valve on your regulator is closed all the way. It probably is but it's a good idea to check.

Plug in the solenoid on your regulator. You should hear a metallic click sound when the solenoid is powered up - that is the valve opening that will allow gas to flow from the canister through to the gas outlet. When the solenoid is not powered, the valve will close and no gas will flow.

The "needle valve" near the gas outlet is how you will fine tune the flow of CO2 into your aquarium. Open it just a bit and wait until you can see large bubbles inside your diffuser. Shortly after that, thousands of micro-bubbles should come rise into the water from the ceramic membrane on the diffuser. 

You'll want to fine tune how much CO2 is being used. Our recommendation is to start at one bubble every two seconds for every 10 gallons but that is just a starting point. You can adjust the bubble rate using the needle valve on your diffuser - keep in mind that it takes about a minute for the bubble count in the diffuser to reflect the new setting, especially if you are lowering the flow rate. Eventually you'll want to fine tune the rate so that the CO2 monitor turns lime green but for now, start at the recommended setting and pay attention to what happens to the microbubbles!

This is the moment of truth where you can observe how your water is flowing by following the bubbles. Unless you are feeding them into your filter, you want the micro-bubbles to remain in the water as long as possible and disperse throughout your aquarium. If most of them are rising to the surface, you will need to reposition your diffuser somewhere else, where the current flowing the right way. If you cannot find a good spot where the CO2 remains in the water spreads through the aquarium, consider feeding them into your filter or getting a small powerhead or pump.

PART 5: FINISHING UP

Set up your dropchecker or CO2 monitor. This is critical as it allows you to visualize the CO2 concentration in your water so that it is not too high or low. 

You'll want to set up the solenoid on a timer to turn on and off with your lights or better yet, turn on 30 minutes to an hour before your lights do. That way, when the lights turn on in the morning, there is already plenty of CO2 for your plants to start photosynthesizing immediately. In nature, the early morning is often the most active photosynthetic period for aquatic plants as CO2 levels tend to be at their highest right after sunrise so many species are roaring to go right at first light.