Looks good, why don't you plant the Hairgrass anyway?
I think that the plants aren't pearling properly, it seems that when people introduce plants to tanks they appear to pearl straight away, even in tanks where there is hardly any CO2 present or high lighting. This could be because when the plants have been exposed to air they recieve quite a large amount of CO2 and so they would have intense photosynthesis and once underwater, produce visible oxygen bubbles. This is something I have happened to observe, it may (and quite likely) be completely wrong. Your plants should pearl anyway in your conditions, I just think it can't be straight away. That's why when you first put them in your tank they pearled, and don't pearl now.
Cheers,
Mike