Hi you all,
I want to share some solutions that I applied to problems this kind of systems have. So you will avoid the same situation I had with it.

1. If you give the pots a slope of 20 degree (some manufacturers recommend 10 degree - in my experience it was NOT enough) you will find that not water will remain after each draining and you will avoid root rot.

2. These systems tend to be clogged by root growth, sometimes the plant in the center of the pipe line clogs the line and water stays in the last pot(s) without being able to drain. And doing a line flushing everyday is almost impossible (pit...). What you can do is to add a small piece of line with a plastic faucet at the end of the pot line, after the last pot, so each day you only need to open the faucet and see if there is water returning there, if water is returning it is because you have a problem (clogging) in that line, then you look for the pot which is clogged and cut a little bit the roots and flush the pipe line (not neccesarily if it is a minor clogging)

3. These systems require two water pumps, one for flooding and one for draining, if you have your grow far from you, or you need to leave your grow unattended for more than 24h, you can add an extra pump to each cycle, draining and flooding (with "Y" connector), so when the system (timer) gives the order to flood or drain two pumps will do the work instead of one. You will have more flow in and out (so you will need to adjust the timer to the water flow), the extra water flow will not hurt your plant roots as if a pump fails and you are not around to fix it. Growers with security issues should do this as you never know when you will be forced to be far from your grow for several days

I hope other experienced members can come with more ideas/solutions about these hydro systems
Peace and hope this can help others