Hi guys, I'm new to this and wondered if someone might be able to help me?

I have setup my planted tank with a number of plants, which are in JBL Aquabasis fertiliser substrate stuff with 3mm gravel on the top. The issue I have is my plants started to go a bit brown so I bought the JBL BioCO2 q00 with the vario diffuser that goes in the tank. After hours of hardly any bubbles a placed the reaction flask on the top of my tank where it is warmer then the bubbles started to produce, but I'm only getting 1 bubble every 12-15 seconds and these are big bubbles that seem to rise to the top of this spiral diffuser and then just build up until one big bubble blurts out the top and thats it. It has been like this for 3 days now.
I was expecting lots of fine bubbles to come out through all the little slits in the diffuser but still I get large bubbles that do nothing.

I believe that system is DIY CO2.
I would empty the canister out and use your own formula which consists of sugar, yeast and baking soda.
You can make your own system with a 2L soda bottle also.
Here is a very good article on how to do it.
http://www.aquahobby.com/articles/e_co2.php

You should also be using Micro/Macro plant food.