Lepisosteus platyrhincus;3893345; said:
.25 is high,b ut what are ur ph and temp? this affects the lethality of it
i keep low ph for this reason(all my tanks not just my gar tanks) even though i never have ammonia in most of my tanks. higher temp makes it more leathal as well.
let me find my chart......
temperature and pH aren't going to be major factors when the ammonia is already that high...that's the big issue. with the water changes it will be kept under control, but if the tank isn't cycled properly, it will just try to cycle again when bioload is increased. also, if you can keep a stable low pH, that's fine, but there is much less room for error when you keep your pH low...with gars, they benefit from neutral pH or even higher...as this will give you some buffering capacity in the water...as waste accumulates, pH drops and ammo spikes, with a higher pH you have more room for error.
all that being said, your best and fastest bets are either getting some biomedia from a previously established tank (i would get it from a friend or from an LFS you can trust -i.e. wouldn't have some level of disease-) or purchase some bacteria colonies to establish your biofilter faster (can be expensive, but beats waiting 3 weeks or more). good luck--
--solomon