Changed the 4dkh solution and now getting much less strange colours, so must have been dodgy solution.
Things seem to be running nicely, 1point ph drop before lights on, full EI, steady growth that I have trimmed a few times, have only been running one t5 light as was getting scum on surface but even reducing the light hasn't seemed to rid this so the plants can't be 100% happy, really want to figure out what the cause is!!
Got some cherrys and amano's, they are fun to watch, bit scared of gassing them tho, so slightly too low co2 could be the cause of surface film, but I would have thought the 1 ph drop and lower light would mean plenty of co2.