Well by thorough cleaning, i meant only
siphoned the gravel very well, nitrates very low.
I didn't clean the filter and I only changed 30% water.
How could that cause PH to crash? Am I removing
hardness when I clean off excessive Nitrate?

After a 50% PH went from 6 to 6.5.
Then after 12 hours I added 1tsp baking soda (tank is 33gal)
I am back at PH 7.5, and KH is back up to a whopping 60.
Fish seem to be very happy now, but as everyone says on
this group, baking soda is only temporary. I will keep an eye on it.
....Kodiak

"BErney1014" wrote in message
...
Anyone with experience using baking soda, please help.

I have used it for many years. You will be better off using Equilibrium if
you
have a low GH too.
Your thorough tank cleaning may have started a downturn and the low
carbonates
didn't help. A higher level of KH and GH is necessary to maintain
beneficial
bacterial. You can get specifics, exact levels, from Aquatic Eco System
specs.