The 27 gallon cube tank is almost done cycling and I noticed today when adding an airstone, the force of the bubbles caused a slimey film that had built up on every surface in the tank to peel away and the tank was full of all this transparent stuff!

I had 2 large plastic plants that I have since removed but shook off as much of it in the tank right before. Fortunately everything was sucked up into the canister filter in about 6 hrs and the tank is clear again. I am wondering, was this a beneficial bacteria build up and if so, should I not disturb the new filter for a while so it establishes nicely in it?

Still getting a reading of Nitrites so it's not ready yet. I did follow the instructions to the letter on the bio booster I have been adding so no overload there. Also added Stability but not Prime as I wasn't sure if I should yet...Should I do a water change yet or wait until there is zero Nitrites?

Yes I used another brand of beneficial bacteria AND water conditioner from the lfs in the beginning and now started using Stability. So I will do a big water change and use Prime next. I also had an opportunity to try Seachems 'Clarity' but with mixed results. The water was crystal clear after 36 hrs but it left a distinct yellow tint to the water so I am glad I didn't use it in the new system!

It wasn't algae was it?? It doesn't sound like something algae would do but I dunno  It could have been some residue off something in the tank such as the gravel, fake plants, etc. Anything like that in the tank that could have caused it?

Are you showing any nitrate reading at all?
That film was probably some algae starting to grow.
It always starts out as a film on the glass and then you see blooms as it grows more.
It's good if you see the algae.  That means your tank is almost cycled.
I would just leave it until your tank is cycled and then you can take an aquatic scubber and remove it.

Thank you for your replies. Hanna, I don't have any driftwood in the tank or live plants yet and the slime wasn't on the tank walls at all. As for the 'clarity' product, I wondered about the colour (dark brown) and that it may have gone bad??? Nossie, overnight it has been completely removed and I think it may well have been that there wasn't enough water movement in the tank allowing the slime to adhere to every part of the plastic plants I had in there. I gave it a good stir with a high powered pump and airstone and just added a full capful of Prime to hopefully reduce those nitrites. When I set up the Rena Filstar filter, I installed the spray bar so that the surface is constantly moving but I guess it wasn't enough. Maybe I will switch to the jet nozzle instead. Nitrates are present Minde between 5 and 10. It looks crisp and clear  

*just attached a pic of the Clarity and it's colour does this look the same as yours Hanna?

Sounds like you solved it the problem, April Good luck with the rest of the cycle!