citroen c5 x7 air bubbles in hydraulic system

[verdi]

Hi All
After a firm ride I checked that there are bubbles air in the LDS reservior. I bleeded the system till the LDS became clear. (Bleeding as per Marc procces)

1. LDS cap off.
2. Start the engine.
3. Setting suspension in high position.
4. Setting suspension in low position.
5. Turn the steering wheel slowly lock to lock (do not hold the steering wheel at the lock limit!).
6. Return steering wheel to centre position.
7. Engine off.
8. Wait for all the bubbles to disappear.
9. Check fluid is between the marks in the procedure.
10 Repeat as necessary.
11. Raise vehicle to normal height.
12. LDS cap back on.

The ride was improved but after a day I got the same issue. bleeding again and so on...
No visible leak.
No loose of LDS.
I've checked the Steering as it appear in another thread and found it dry.
A few questions
The meaning of air in the system should be a leak from some where?
At past the car was hang without pick her to max. highest and opening LDS cup - could it made the air go to the system?
should I do a bleeding with 0.5 bar pressure?
No wet areas, but apart of the boot on the front right strut has different dark color - May be any connection? - again it doesnt wet.
Any advises Please.
Many Thanks.

[GiveMeABreak]

When fluid dries or becomes congealed it will turn a darker colour, so you may have a fine strut leak. Best thing is to gently clean the area up and then check to see if you get any fresh oil there over the next few days / weeks.

[verdi]

Thanks Marc
I will look again on it.
Is there any hose on the strut which cause any leak?

[GiveMeABreak]

Unlike earlier C5s there are no fluid 'leak back' return pipes, so any weeping or fluid there not from a spill is likely to be a leaking strut. These are made of bonded plastic to metal, so can't be repaired, requiring a complete strut replacement.