Just installed an external filter to replace my internal filter. That has solved the plants getting pushed around.
The plants however are mostly dead by the looks of it. I have been dosing liquid ferts, had a lot of root tabs for roots yet pretty much all plants seem to be dead or dying. The water is also cloudly (maybe just due to moving things for external filter) and I have very high nitrites. Any ideas?
Careful, you have crypts in the tank. If there has been upheaval, then they will most probably melt, "cryptocoryne disease". They will usually bounce back, but look absolutely aweful in the mean time. Also, if you have plants with emersed rather than submerged growth, namely your swords, they will need time to shed their emersed growth and adopt submerged growth. Again, they will look like they are dying.
Keep up with your maintenance and wait. Remove dead or decaying leaves.