You may not have anything in your tank that is utilizing the calcium amount that your dosing, so there fore it will build up in levels.........You need to figur eout how much calcium your tank is using up, and dose accordingly........With a cal level of 900 I would have to belive its like a snow storm in the tank. Is it precipitating out in the water? I run 460-500 calcium and my tnaks do fine. The big thing with zenia, especially the pulsing type is ph. I would suspect your alk is low as it usually runs opposite of the cal. and thus yur ph is probably low as well. Xenia like a 8.2 or higher ph to do their best. A water change wil help rediuce calcium levels, as will time. Do not add any more calcium to it until levels drop to where they should be. Take a alk test and a PH test to see where yu stand.
In reality your overdosing the calcium since its building up a high residual level, since evidently your tank is not utilizing the amount that your adding........You may want to adjust it to say half that amount every oter time that your doseing now, and see how it comes out. Its always best to start off at half of the recomended doses and work it up......its much safewr, but high cal wil not generally hurt anything longterm.
