Epoxy

[Half-Pint]

@Fritz thanks for the offer but its only R50 a tube which is almost the same as postage. Also this project has been going on for too long now I need to get it finished.

@sharkslayer as far as I know the gardena fittings are PVC. At least that's what they are labeled. I will post a pic over the weekend I'm sure things will be clearer then

[BJR]

Find it at most good Hardware stores. Mix 1:2 ratio , takes about a day to set and maybe 2 days to cure properly. Colour is off-white to clear when dry. Two little red tins for smaller applications and do get larger tins. 

[Mussel Cracker]

is the ball value steel.??

[Half-Pint]

Nope all standard PVC

[Mussel Cracker]

then pvc weld is the best thing...if you having a problem just give me a call i will come check it out and see how to sort it out...

[Half-Pint]

I have tried PVC weld but it doesn't dry hard enough. I will give the epoxy a go if that doesn't work I'll have to relook at my design

[AndriesH]

hmmmmm, interesting.
110mm Co2 diffuser in a fish tank = 10 000L tank.

Be aware that CO2 causes imbrittlement in most plastics - PVC too. so you will have a limited lifespan of your pvc product.
You mention pump?
What for, how are you getting producing CO2.
If you are brewing it, you will have pressure already, if you are using sodastream bottle, you have pressure already.

CO2 must only be added during lighting hours. At night, plants produce CO2 and with the extra gas, you will crash the pH due to the formation on carbolic Acid.

Get a CO2 rated back check valve and CO2 rated tubing.
Back check is vitally important as the CO2 dissolves into the water and the water levels 'creeps' back up the diffuser.
If you leave it, it will creep into the piping and send your tank water over the edge and onto the floor.

[Half-Pint]

Andries I simplified terms for everyone because I didn't feel like explain external canisters etc so I just put pump instead. I have everything sorted wrt the CO2 system as well as my parameters KH etc I just wanted to try an inline reactor to minimize the hardware in the tank. If I can't pull off the reactor I am going to be using a powerhead to diffuse.

[AndriesH]

No probs.

Easiest thing to do is to mount a cup / glass upside down in the aquarium close to a circulating pump.
Fill it with CO2 in the morning and adjust the quantity of gas according to what is left in the glass in the evening.
Use a piece of hose attached to a Sodastream machine and hold it under the opening of the cup to fill in the morning.

Remember pictures when it all is running.

[Half-Pint]

Andries I am using a 2kg co2 fire extinguisher and dual stage reg with a solenoid for my co2. So I need a decent diffusor or its like buying a pentagon and using lucky star pilchards for bait

[AndriesH]

he he he.
AKA BMW M5 @ 60km/hr