THC dosers can control the injection of liquids for your hydroponic culture.
THC can control pH of your solution and injects acid (or base) in your solution. To this end THC engineers implemented control algorithms that can adapt to the volume of your tank in order to reach the target pH value with the best accuracy and the minimum of time.
THC dosers have a BNC connector to plug a pH probe. this is not mandatory, but it is strongly recommended that you control your pH this way. pH probes are very cheap, it would be a poor choice not to leverage on this base feature of the THC dosers.
THC can control EC of your solution and injects nutrients in the right proportions. To this end THC engineers implemented algorithms that can adapt to the volume of your tank in order to reach the target pH value with the best accuracy and the minimum of time.
This not mandatory at all, you can also simply rely on the dosage of the nutrients vendors. In such a case (no probe), you need the THC to control water, in order to know the water volume added and injects the nutrients accordingly.
You have a water supply (lucky)
If you have a water supply near your culture (lucky grower), THC can manage water refill by controlling an electrovanne.
As an alternative you can also have a separate clear water reserve and THC can control a 12V pump in order to refill the solution when needed.
You haven't water supply (unlucky, but it's ok)
If you don't have water supply and no space for another tank, don't worry: you will simply add water manually and the whole control systems will adapt thanks to the pH and EC probes, that will control injects what ios needed for your culture.