dKH in cycling tank fell from 6.7 to less than 0.5!
I'm setting up a new 24 gallon aquarium with Aquasoil, without another aquarium to seed the bacteria. The soil leached ammonia into the water and I've been monitoring the parameters, waiting for the ammonia to disappear. I tested the kH on the first day but haven't tested it for a few days.
On the 19th I tested the tank for leaks and tested the tap water while I was at it. The dKH was 6.7. On the 20th I put the substrate in and that evening I tested everything except dKH, thinking there wouldn't be any reason to see it drop.
I tested it today and the dKH below 0.5. This is with a Salifert test kit so it's adequately accurate. I tested it again, to make sure I didn't make a mistake, and 3 times, it tested about 0.4 or 0.5 dKH. I've added 11 grams of sodium bicarbonate (regular, not anyhydrous) to correct it back up to around 5 dKH but I've never seen carbonate hardness fall this fast.
Has anybody else seen this happen? There are no plants, no lights. Just cycling the ammonia spike... Am I going to have to test my dKH daily for a while when I introduce plants next week?
Oh and I don't have a GH test kit. I guess I should go get one :P.