Its not bad. It could be pearling, or damaged leaf/stem. Or a sign of new growth like a new stem or leaf.

 

Most of the bubbles are coming from places I have trimmed, but some of them are coming from places that are fine, and healthy

 

Dont worry its normal for plants to do this after a trim.

 

How long does it normally happen for? its been doing it for 3 or 4 days

 

mine do it every time the light it on for over 4 hours it is either damaged plant tissue or your plants are photosynthesizing I took some pics of my bubbling plants today heres one:

to see them all go here:
http://www.aquaticplantcentral.com/forumapc/aquascaping/49082-jazzlvr-s-75-gallon-planted.html

 

Called pearling. It happens when the plants photosynthesis. It is especially high when they photosynthesis a lot and the water is saturated in oxygen.

 

Healthy plants produce oxygen. Oxygen supersaturates in water at a mere 12 ppm. The bubbles you are seeing are oxygen bubbles. It's a great sign that you are doing things right.

 

accept I have green water, what causes this and how can i treat it.

 

Green water usually happens when the bacteria balance is upset. This can either be because of a newly setup tank that is still establishing its bacteria or because something killed off the already existing bacteria. Once you get the tank cycled again or cycled for the first time it should clear up eventually.

 

A UV sterilizer will quickly eliminate green water as well

 

I get pearling on my HM and other plants just after doing a water change with a bit colder water...
Green water I heard you could use daphnia (if you can remove the fish in the mean time)....

 

my new 75 gal tank has been up for 6 weeks, have added a few fish, done a 20 gal water change, about a hour after i was done all the plants were sending up bubbles, looked like it was snowing up. it was very cool. that was several weeks ago. after every weekly water change i get bubbles, but nothing like the first time. every thing checks out ok. i'm not to worred about it. my tank is doing good and looking better everyday. anybody want some sword plant runners....swords are goin crazy.....