Sodium Carbonate and bicarbonate

[irvp13]

I was in the market for alk and I saw that some companies sell soda ash rather than baking soda.

Whats the diference between sodium carbonate and bicarbonate when used to dose Alk?

What happens to that Na molecule?

Thanks

 

[homegrowncichlid]

2NaHCO3(s) ? Na2CO3 + H2O + CO2

Soda ash has a very high pH around 11 and no buffering.
I use to make this stuff up by baking baking soda in the oven or in a pan for a minute or 2, until the powder boiled and flowed like water. Then I'd use it to get the pH up really fast back when I was breeding African cichlids. Not sure why you'd need it in a reef system, since adding it will break the buffering capacity of the pre mixed salt mixes.