It may be that you will need more CO2 than the Hagen can deliver due to the size of the tank. Depending on your filtration (surface disturbance) and your water, you could get a good response though. I think that you need to get the Hagen system running and see what effect it has when it is going correctly.
Your particular water chemistry is very important. If you have not tested for starting pH and KH, do so now. Go buy a test kit if you don't have one. This is critical to know before you start messing with the water chemistry. Lots of good info here, spend some time reading.
The Hagen diffuser works great unless you send too many bubbles in at one time. The Hagen system mix is amazingly regular in the bubble production, no doubles, ever. Even a single DIY yeast bottle using the diffuser, alone, without combining with the Hagen bottle, might send out two bubbles at the same time which are so large that they race through the diffuser, and one bubble is pretty much wasted. I am currently doing that in the 20 gallon tank, and it is only a problem when the bubble rate is pretty low. So, two bottles are workable, if you decide that this is necessary. But, make an educated decision, don't just jump in and do this.
Really, you will just have to experiment. Start with what you have, get it working correctly, test and see if the results are adequate. If not, try adding a second bottle to feed into the diffuser. If that is still not enough, you may need a different input method to be able to use more DIY bottles, like a power reactor of some sort.