heh, funny story... I love how other users seem to go through similar situations as I do at almost the exact same time that I go through them...
My tank just crashed too =( Something happened while I was gone to California for 2 weeks and caused stuff to die. My sump was also new, I'd say about ~1.5 weeks but I used Silicon that was supposedly "Aquarium Safe"
Like that but in a teal color... Has a lil fish in the bottom left.
Anyways here I am about 2 weeks after I got home from Cali and I think I
FINALLY got my head above the water and my Ammonia and Nitrite are diminishing down close to 0. I had already lost most my livestock... =(
BUT, my frogspawn is still hanging in there! Along with a few mushrooms whos faces look like wet dripping paint xD
AND, I managed to keep all of my fish alive!!! (2x clowns, firefish, chromis, and Flamehawk.)
First thing I used when I still had lower ammonia readings was:
I believe this helped keep my fish alive through the process. What it does is bonds the ammonia in a non toxic form until the bacteria have a chance to convert it.
Then what I did in an attempt to fast track my tank back to where it was supposed to be was add in a beneficial bacteria supplement. Now at first I was putting in small amounts at a time. I would recommend 3x to 4x the recommended amounts if you have livestock in your tank to help speed things along. I finally started dumping that in pretty decent amounts after my ammonia had spiked up to around 5ppm! and got results quickly after it was back down to ~.25 ppm.
Anyways I think I finally got my head above the water on the vicious 'Cycle' and was able to same my fish at least, and possibly a few corals.
I don't know what initially caused your cycle (Silicone or not) but if you can get rid of that you can start the battle on getting your bacteria levels back in place. Keep in mind I was doing 10-30% water changes daily to help keep the toxins diluted. I would suggest some of that beneficial bacteria to all and every time you have a change in bio load or new additions (Like a sump) to add some of that in to prevent a tank crash.
Hope this helps you out and your little friends make it through!