What Happened?

[kcharley]

Having found a good deal on a new 20 gal tank and stand, I set it up, dechlorinated the water as usual and moved an established filter and five gallons from a 10 gal tank. I also moved the 11 cory's that were in the old tank and added one large gourami. Suddenly the filter which for several months had kept the cories on 0 ammonia and 0 nitrite is performing poorly. Ammonia was .5 and nitrite was .25 the next day. I have gone through several days of 75% water changes now. Progress seems to be occurring as ammonia is 0 - .25 and nitritie is .5 the next day. (Of course, I continue to do 75% water changes daily and will do so until readings are 0.)

So any ideas what happened?

Did the cories put off so a light a load that the filter wasn't cycled at all?

The prior tank had a playsand bottom. The new tank has black onyx sand. Could the sand be the problem? I know ADA AS can leach ammonia but never heard of onyx sand doing it.

Thanks.

Greg

 

[greenscooby]

Just read a seachem brochure, and there is a small, small, small chance that onxy sand can upset your water stats, sorry to be the bearer of bad news.

 

[aaronnorth]

disturbing the substrate releases ammonia