You are quite right high pressure is either mains supply or using a high L/H (Gal/H) pump.
To my understanding a High Pressure system will operate at 4 Bar or higher.
For this 13mm (inner dia) LDPE pipe is recommended and if adding 4mm (inner dia) tubbing, 14-16 PSI (3 Bar) is recommended as the highest pressure to use or you will blow your lines.
For a high pressure feed system (using nutes) a pump of 500L - 1000L is recommended to give a good pressure. Then a pressure regulator is added to regulate the pressure going to the 4mm (inner dia) tubes and fittings which are often rated at 17 PSI.
Then an inline filter to help preventing blockages.
At the end of the 4mm (inner dia) tubes "PC" Pressure Compensated drippers are added.
PC drippers/misters regulate the amount of feed allowed through each dripper such as 0.5, 1.0 & 2.0 Liter per hour for example.
A manifold can also be used for 4 mm (inner dia) tubes.
The Octabubbler has 8 out ports and the manifold has interchangeable discs for 0.5, 1.0 & 2 Liter per hour flow rates.
Low pressure can be from a passive source such as a hydro bag system.
However a low pressure system can be also using a pump, with unregulated flow ports or drip rings
Low pressure drip is often used for low numbers of plants because the further down the pipe the lower the flow, which means some plants will get a ton of water and the ones at the end won't get much, if anything.
To this end adding flow valves at each station will help equalize the delivery of nutrients.
That is about the extent of my understanding so far, more research needs to be done.
I will end up buying the parts to build a high and a low pressure systems, using 13mm (inner dia) exclusively as well as 13mm (inner dia) with 4mm tubes.
So in total I will build 4 kits 2 high pressure and 2 low pressure
- high pressure kit 1 - 13mm (inner dia) with PC/PR drippers
- high pressure kit 2 - 13mm (inner dia) & 4mm (inner dia) with PC/PR drippers
- low pressure kit 1- 13mm (inner dia) with unregulated drippers/drip rings/hydro halos
- low pressure kit2 - 13mm (inner dia) & 4mm (inner dia) with unregulated drippers/drip rings
Pressure regulator, will only be used with high pressure kits.
An inline filter will be used with all kits.
all comments welcome which can lend a hand!