Another tip from a user of this reactor is to put a little bit of vaseline on the threads of the main reactor body. One down side of this reactor is no one seems to know where to get a new rubber seal should it be broke. CO2 has an habit of perishing plastic and rubber making it brittle hence co2 tubing being differentfrom airline tubing. When I used diffusers placed underneath a koralia the last couple of inches of cable would stiffen up and not be as flexible as the rest which was outside the tank. The vaseline keeps the rubber seal a bit more flexible and also aids when you need to take the reactor to bits. When it has been left for long periods the reactor body is quite difficult to unscrew with little you can grip. Like Alistair mentioned when unscrewing the body keep well away from the co2 inlet. I have the mobile number for the sera rep so I may give her a call and see if she can get hold of the o rings. Best to have spare and not need than damage it and not have one!
Regarding co2 diffusion, I was in the same train of thought as yourself. There is definitely a big difference when using one of these compared to a diffuser. It was highlighted to me over Christmas hols when I would leave my lights on for decorative effect until quite late at night( sometimes 2 AM or later) That's drink for ya
I noticed that even though my co2 switched off about 7.30 in the evening my drop checker would just get yellower and yellower even to the early hours so I started knocking it off a bit earlier. Doing some PH tests with a PH pen and standard liquid kit I found that my PH at lights on was around 6.2 and dropped to about 6.4/6.5 at lights off so indeed the co2 was not just getting higher and higher like the drop checker suggested.
Even 4 hours before switching lights on just and so got the drop checker a green colour for lights on. My conclusion was that as we already know the drop checker is displaying 2/3 hours behind the actual levels and as you have noticed due to the co2 give or take being fully dissolved before it leaves the reactor the drop checker seems IMO to react a lot slower than it would if there was a fine mist of bubbles floating around the tank which is what you would expect with them entering the DC.
Switching over to the reactor from diffusers has taught me that firstly they do indeed need to switch on a bit earlier than a diffuser as you don't have the misty bubbles on the leaf surfaces which work for the plants quicker than co2 being dissolved in the water column and secondly that drop checkers do take a little bit longer to react to the changes. The combination of the two gives the impression that co2 needs to be on/off earlier. Generally people work to two hours before but if you use the drop checker as your guide it will give the impression 4 hours is more realistic. Doing real time PH tests is the best way to check your co2 profile as long as you do them properly and take into account other acids that could be in the tank other than the co2.
One thing I did also notice was the Sera type long term co2 drop checkers, although not as pleasing on the eye as the glass type ones did react quicker to co2 changes. To summarise diffusers give a false early reading and reactors give a false late reading. Just use the drop check to make sure your gas is on.
