What Have I Done?!

The filter bacteria are a lot more robust than people realise. It does take quite a long time for them to actually die; they become dormant first. Because you switched back on within a few hours they shouldn't have come to any harm. I had a planned power outage last year for 8 hours, and your filter won't have been off much longer than that. I have also forgotten to turn the filter back on after a water change and only discovered it next day without anything happening to the fish.
It is common for filters to spit out gunk when turned back on, you'll remove that during a water change. Your ammonia and nitrite had risen as the water wasn't going through the filter and the bacteria on the surfaces couldn't cope with all the ammonia the fish made during the night. Once the water started to circulate back through the filter, those bacteria would have started to do their job.

Keep an eye on your water for the next few days just to be sure, and feed the fish slightly less than normal (less food = less ammonia). And water changes if the tests show a reading over zero - hoover up the filter gunk at the same time.





And ask Santa for a timer for the lights 

Fair enough.

I have just bought a small moonlight LED which I will set on a separate timer to turn on shortly before the main tank lights go out and turn off an hour after the main lights. Well, I say bought - I got it on Ebay and selected delivery to Argos as I didn't want it caught in the Christmas post, but the seller used 2nd class post so goodness knows when I'll actually get it  It's for the big tank which is in the dining room so I've been leaving the room lights on for an hour after the tank lights go off. Once it's been up and running a week or so, I'll put a review in that section.

I use electronic timers for my lights. They usually have a button that you can press to temporarily override the programme. Of course, if you're half-cut it may be a good idea to label them...

Sue, I am planning on getting a moonlight LED strip for my forthcoming Roma 240 too.

my 5 ft tank has one of the most complicated light  systems i have ever saw but i grown to like it now because it has both day and a light night light built into it at the pre set time in the morning it gradualy increases  from its night light up to full day light over 30 mins then during the day it goes into 5 seperate cloud cycles were the light gets a bit dimmer to simulate clouds passing by then at the end of the day the light dims down again over a 30 min period to its night time setting but its night settings run to a moon cycle so it gets a little darker every night over a 14 day period till eventually it gets to a point were the is no moon (no light for 2 nights )then it starts to get a little lighter every night till get a full moon .
sounds very complicated and it was but once mastered its a great bit of kit that i have to admit i would be lost without now