injecting co2?

So, here's the thing. Since you add baking soda and crushed coral to your snail tank, it's safe to assume that it's higher in KH. The other tank could low(or none) in KH or just lower than the snail tank. Depending on where you are, you could have absolutely no KH. My API test changes color on the first drop, meaning, without any additions, I have no KH.

Suspect your test kit before your start dumping a lot of stuff into your tank. It's also possible something is in your other tank(not the snail tank) that's affecting KH. Have any suspicious rocks?
 
no rocks in the tank but i added some crushed coral and baking soda to my tank in question and the test changed in the first drop.so if both my snail tank and my 29G change on the first drop after adding baking soda and CC is there even any way to increase my KH further?I really don't want to have a PH crash after setting up the CO2
 
You said you have no KH if the test turns blue on the first try?Well how come it didn't do that when i added 12 drops?When i added the coral and baking soda it read on the first try meaning i have no KH?How could this be?it seems like the additives reversed since i added 12 drops and it didn't change but after adding CC and BS it changes on the first drop?Will the KH test not even change from yellow to blue if there is 0 KH?
 
Try another test kit or take a sample to a LFS that will test it for you.
 
AquariaCentral.com