1ppm ammonia is common in areas where the water is treated with chloramine. Treatments such as Prime, Chloram-X, Safe all bind the ammonia while breaking the bond with the chlorine. My source water has chloramine, I do high percentage water changes (80, 90% is typical) and have never had an issue (I've used Prime in the past, currently use Chloram-X and will be switching to Safe next as it's cheaper). I'd be surprised if 20 gals of 1ppm ammonia would've affected the ray anyway, given the overall dilution of the water you added: assuming a 200 gal system including the sump that's .1ppm when the makeup water mixes in and the filter would've removed that in short order.
Presumably the water company has switched to chloramine, it would be worth checking their website or giving them a call to find out for sure.
Sorry for your loss, whatever the cause.
Presumably the water company has switched to chloramine, it would be worth checking their website or giving them a call to find out for sure.
Sorry for your loss, whatever the cause.