EMERGENCY! Red Devils Calling Dr. Solo

Hi Ingrid and all,
I know this is not the place to post but I need your advice.
(yes it's me again, btw, Oscar and Felix are doing great thank you!)

I have a 220 gallon tank with 6 red devils about
4" long each. Unfortunately the tank was new when
I started (Jan 4th) so I used Biozyme to jumpstart the
bio filter. The Ammonia spike was not so bad i never
hit above 2ppm and just for a few days and i did a few
25% water changes just to be safe.

Unfortuanately the Biozyme dosen't seem to be working
on Nitrite as well as it did on the Ammo. I think I'm
between 2 and 3ppm but it could be way more, i can't tell
because that's where my test kit tops out. The fish were
fine untill today so i did a 30% water change today ( last
water change was about 3 days ago) and the reading is still the
same, topped out on the Nitrite scale, it's as if I did nothing!

I don't have access to Biospira, but i wonder if it's better than
Biozyme? Has anyone out there tried "Cycle" ?
The fish are now sitting on the bottom of the tank, not moving is that bad?
They are not at the surface gasping for air, is this a good sign?
Am I gonna lose my fish? Is the Nitrite spike just as bad on the fish
as the Ammo spike? Will there be permanant damage or brown blood disease
etc? I have a 0.1% salt solution, and a Huge 6" airstone with a big air
pump,
will this help oxygenation? I understand that nitrite competes with oxygen
to get
absorbed in the bloodstream, but is there permanent damage? I'm gonna do
another 30% water tomorrow, is there anything else i should do?

PS: filtration is 2 Aquaclear 500.

....Kodiak