When I bought this Xantia in March 2012 I fitted a full set of new IFHS spheres from AEP.
Ride quality has generally been very good (particularly after fixing an air leak on tank to pump line and performing the tank modification) up until about 2 months ago when I started noticing the ride wasn't what it should be, and decided that I would replace the spheres again next spring, after only 2 years.
Well in the last week the ride has got much worse, very quickly. I seldom do Citrerobics or lift the suspension fully up, but I've done that a few times over the last week and the ride has got dramatically worse since then.
At first I thought maybe the ride height was too low or too high due to sticky height correctors, (I did drive through a foot deep flood last week which I thought might have caused the height corrector linkages to get soaked and start seizing) but after a few bounce tests I think that I have two punctured front strut spheres. 
In "soft" mode both front and rear suspension have quite a bit of movement - so the hydractive spheres are ok at least, or at least not punctured. But in hard mode (engine off, doors closed for 30 seconds) the front suspension is absolutely rigid with no give at all even with my 88Kg bouncing on it, and it wasn't like that a couple of months ago.
The rear suspension in hard mode is also very very stiff although has a very slight amount of movement.I know the damping is very heavy in hard mode making it difficult to judge with a bounce test but you normally can at least get an inch or so of movement if you bounce it hard but I can't really get any movement at all in hard mode. When driving every time it switches to hard mode (taking off from an intersection or turning sharp for example) the ride is suddenly obviously hard, bouncy and fidgety.
In soft mode it tends to "rock" side to side over road undulations, as well as feeling like there is a lack of damping for parallel undulations - both signs of low gas pressure in the strut spheres of a Hydractive 2 system.
Fully pressurising the suspension with spheres that are very low in gas runs the risk of puncturing the diaphragms, could it be that all my strut spheres were very low in gas in the last couple of months and that when I did a few sessions of Citrerobics in the last week that the front strut spheres have gone pop ?
The rear ones if they haven't gone pop can't be far behind.Anyone had such poor sphere life before ? They've only been on the car 21 months and done about 8000 miles, and if they're not punctured they're very close.
I've normally got at least 3 years out of standard spheres and the long life types last about 10 years, so to say I'm disappointed is an understatement. I'm not relishing the thought of having to change spheres in the middle of winter, when I thought they would last at least until the spring!
Also, does anyone know if its possible to obtain the long life multilayer diaphragm front spheres for a Xantia, (the ones with the three dimples around the filler cap) or do none of the after market companies do them ? They really do last a long time compared to the standard types - and I notice from service.citroen.com that my Xantia was originally fitted with them.
At that price I'll just continue to buy £20 IFHS spheres and replace them more often 
