pH Controller Safe?

I ran an SMS 122 for years in my tank with CO2. Never had any problems and it did a good job keeping my pH very stable while allowing me to push my CO2 up to 35 ppm.

If you are buying new get the MC122. Its the new model an not so friggin ugly.

Oh I will add also, after a five year break I pulled out my SMS 122 and it was unfortunately dead. So I ordered a MC122 . So while I was bummed that it had died, I liked having it enough that I dropped the coin for another one.

First, a pH drop due to CO2 isn't the same as a true pH drop. Second, most fish will do fine with the pH adjusting due to CO2 and just watching your fish and how they behave, using a drop checker to monitor CO2 and running an airstone at night are enough to not need to spend the 100 or 200 or whatever a fancy controller costs.

I like having my SMS122. It will do one thing that I found I needed due to careless setup. I had a leak at the tank, did not test with soap and the tank dumped the gas. The controller shut off the solenoid and the fish were saved. Would they have died in my tank with canopy without the controller to shut it off? Nobody can say for sure but I feel better having seen it do the job.
When controllers are taken out of service, it is important to keep the probe tip moist as drying will kill it. Just be aware when buying so that you don't buy a dry one second hand, etc. New ones should be shipped with a cover over the end.

Talk to Orlando at Greenleaf Aquariums, this guy has helped me tremendously. I bought my set-up from him and he told me that with his regulator I didn't need a controller. So a buddy told me that I better watch out when my tank gets low I'll have a end of tank dump and kill all of my fish and that's why he has a controller. Well, he has a Milwaukee regulator. So I talked to Orlando and he said not to worry. He said that those regulators are notorious for end of tank dumping and that I had a much better regulator. He was right!