I am a yaysayer when it comes to glut used properly and I know I’ll never win you over; @AbbeysDad
Yes, glutaraldehyde is used in hospitals to sterilize equipment …because it is considered to be relatively safe to use around humans. It also has to be “activated”, by hospital staff before use, to move pH up into the 7.5-8.5 area to make it deadly to germs. This is why we say to throw out the “activator” that comes when we buy Metricide. Seachem makes sure that Excel is not “activated” in this way.
Alcohol is also used in hospitals to sterilize equipment (and some humans even drink it). They even use X-rays on humans in hospitals. Other things some of us put in our tanks that are used less safely elsewhere: Ammonium Nitrate (explosives - Beirut last week), Potassium salts (lethal executions), Hydrogen peroxide (can kill everything in our tank), Muriatic acid (same as H2O2).
These are just samplings that come to mind but, when used properly, can be beneficial. Here is a headline from today’s media “4 US deaths tied to methanol-based hand sanitizers” and, if you read it, you find that the people actually drank it in order to die. Total misuse of a product that works well as a hand sanitizer. Glut/Excel, when used properly, works fine in aquariums. The only harm that we can find is anecdotal, which is also the bulk of the safety that we can show, except that Seachem has performed better studies than hobbyists on Excel’s safety margins.
Answering the OP’s question:
Is there any benefits of dosing liquid carbon along with pressurized carbon? Or can I throw away the liquid carbon?
, I would say that there is no benefit, since CO2, done correctly, should simultaneously provide all the carbon a plant needs and prevent algae via healthy plants.
However, I wouldn’t throw it out, since it can tamp down hair algae on a short term basis with a single, large, dose. If you have Metricide, it does have a shelf life. I don’t think that Excel does and I don’t know about NilocG’s Enhance.