A 29 gallon tank is right on the borderline of wanting DIY with a 2 liter homemade generator and some sort of reactor for the Hagen system is rather expensive once you get two of them and you will need two for a 29 gallon. Or you might just want to go for pressurized. A 29 is in that grey zone, depends on your budget and your time and ability to make stuff out of parts.
You can use the Hagen ladder diffuser and add a larger DIY canister than the Hagen comes with and it will be OK. If you have the $ and can afford it, you will love to go pressurized. You do not need the automatic pH controller.
As for nightime, it depends on the rate you add CO2 during the day. If you sock it to the tank with high CO2 input rates, then you probably need to not add CO2 at night and may even want to add aeration to release excess CO2. If you have moderate CO2 input rates, then you can test to see if you want to shut off CO2 at night. Doing so saves getting a tank refill so soon, and the CO2 level in the AM is lower which may be better for the fish. It very much depends on your tank, the amount of plants you have, the sort and number of fish you have, the surface disturbance that releases excess CO2, and so on and so on. You just have to test to see what works for you.
I ran my 29 gallon with a 2 liter jello mix for a long time, lasted about 4 weeks sometimes 8 weeks. Ran an internal reactor, moderate light plus dappled sulight. I eventually bought a used pressurized system when I got tired of messing with DIY. If you can get a tank at a reasonable cost, say $75 for a 5 lb tank, and an all in one regulator for $90, and add a cheap diffuser like the Eheim for $15, that is fine for lower levels of light near 2.0 wpg. At higher light levels you may need more efficient inputs, I'm not sure, the diffusers work fine for me and I have an internal Plantguild reactor in the higher light tank.