[GpsFrontier]

my question is how fast do i have the drip lines running, i read somewhere that i should have it at about 2ltrs per hour and have them running for 15mins at a time so about 1/2 a liter per plant,

I know it's easy to over think things, especially in the beginning. But it doesn't need to be complicated. All you need to do is make sure the growing medium is moist like a damp towel, but not soaked/saturated like a towel dripping water all over the place when you pick it up. If it's saturated that can lead to stem rot, as well as suffocating the roots.

That's it, no calculating, no math problems here. In this case forget the calculator and time schedules and just use your hands to feel how damp it is. Though with drip lines you do have to keep an eye on the drippers, they can clog from the mineral salts in the nutrient solution.

Since your system is a combination drip/water culture system. If the root system is big enough that most of the root mass is hanging down into the lower tub, you don't even need the droppers at all. The plants will get the moisture/water they need directly from the tub. I forget if you have an air pump running to the tubs. But if not, you should to help keep the submerged roots from suffocating.

am i supposed to use some kind of restrictor to restrict the flow if its still too much with the pump on low?

If your growing medium is getting to wet, you certainly can restrict the flow. A lot of pumps will have a dial directly on it to adjust the flow rate. But if not you can install a cock valve/ball valve to adjust it. Or install a bypass. A bypass is simply a "T" connector somewhere in the line to split the water pressure and flow. Have one side go to the drippers as usual, and the other side go directly back to the reservoir.

is that ok to even restrict a pumps water flow?

Sure, submersible pond and and fountain pumps can have the flow restricted, and it won't hurt them. Some even have a dial directly on them to adjust the flow rate. This adjuster does nothing more than open and close the opening that allows water to the propeller. The down side is most of these adjusters can sometimes easily move if you touch or bump the pump. It's usually easier to just adjust the flow rate inline from the pump to the plants.

So what would you recommend for the drip flow and how long to run it for and how many feeds over 24hrs

Like I said just use your hands to feel how damp your growing medium is. I'm not there so I can't feel it myself. You just need the growing medium to be moist and not soaked, and you only need it on long enough to get it wet. Don't leave it off so long it begins to dry out. You want to try to keep the growing media consistently moist, not going through wet/dry cycles.