OK, your dechlorinator dose is very slightly low and shouldn't really be a problem but I would be tempted to raise it to 1.5mlL per bucket to be on the safe side. Can you smell any chlorine in the tap water?
Your bucket. Is there any chance it could have been contaminated when you made the water change? Could contamination have crept in from any other source?
Whether it goes back to day one depend on what's caused the stall, which at the moment isn't clear. If it's just the change of water parameters it should pick up soon, but then again I would have expected it to have picked up already by now.
Are you making sure your aeration is as good as you can get it?
Is the filter flow noticeably any less than at the start of the cycle?
BTW 5L isn't a bucket. I drink tea from mugs bigger than that!
Okay i'll up the dose next time
.. I can't smell chlorine from the tap water no. I always rinse out the buckets first so don't think they could be contaminated. What kind of things might contaminate it?.. there hasn't been anyghing different near the tank since day 1, that i can think of.
Ive got an air pump with 2 outlets on full blast so the surface is very agitated, I could turn the filter outlet to the surface aswell if this will help.
The filter flow seems just the same.
5 litre buckets.. even they're heavy fingers crossed its just a short period
lol
! Feel like im eventually getting somewhere though 
!
