pH problem as high as 8.8

[kenzu0911]

hi to all,

I have 3 30gals tanks, centralized with 1 50gals sump.
Im at 8th day cycling of my tanks.
I wonder why my pH is that as high at 8.8.
I know and i believe that someone may help me.

Now, i bought my white sand from a hardware,, and rinse them with fresh water twice on the 1st day before cycling.. I put the sands on the 1st and 3rd tank and live rocks too. Then a crushed corals on my sump.
On the 6thday, somebody adviced me to put 20ml of vinegar, then i test the pH again early this 8th day this morning, nothin happened.
So i asked my friend chemist friend on how to lower my pH, he replied me to use a Muriatic Acid. I dont know if it is safe, but i tried putting for upto 8 tbps of muriatic acid.
Im so amazed! my pH lowered to 8.2 in just a few minutes.
Is this safe? how can i maintain my pH to the ideal level?
Please advice me, thanks.

[thurrmac]

[yoki]

[kenzu0911]

And thats my mistake! Your right sir thurmac.. I didnt realize that it my kill good bacteria, because im in a panic mode..
Im starrin at my new tank, wonderin why that was so high?, unlike my 50gals tank, i never encountered like this before, specialy for those whom ive setup their tanks..
Whats wrong with my setup?
Is it the because of the white sand i bought from a hardware in front of cartimar, sir yoki?
I haven't encounter a problem like this before.
Though i havent try usind a sand from that store, i often use a sand from the exporters in sucat.
Though i use a pH buffer, but still nothings change.
I can tell you, it was so high. Sometimes, its color is no longer in the color chart..