how much crushed coral to add?

Hey everyone.. I have a 16 gallon tank and the pH wont rise above 5-5.5 So I am going to go out and buy some crushed coral today.. I am going to put in a mesh bag so that it is easy to remove.. but how much do you think I will need to add?? I do not want to replace my substrate with this just add a bit to help balance it out..
thanks

 

i'm guessing that it's a fw tank since no sw fish could live in that ph... first of all have you tried any chemicals? if so, what? Kent makes some pretty good stuff for ph.but if you want to go the way of crushed coral i don't think you can buy a bag of less thatn 20 lbs.? i don't think it will be a matter of how much you add, but how long you leave it in. keep a close eye on it.

 

Just wondering what type of fishes are in there and why you want to mess with the ph. Usually a low ph is a sign of high acidity, a condition I am not used to or familiar with since my water is highly alcaline. Just curious where it is that you are getting this water from. I have to agree with hooter head on the chemicals. Many products out there will help regulate the water very well. Beware of a fluctuating ph, which can actually do more harm than good.

 

yes it is a freshwater tank... Im not sure what is happening to the water it comes out of the tap at 6.5. my substrate is florite i only have one lava rock ordament and about 8 plants with yeast activated CO2, however my PH was low before I added the CO2.
I have not tried any chemicals becuase everywhere I read it says that htey are bad and you will get a PH rollercoaster.. but if there are some products that work OK i would rather use them i just thought the coral was kinda foolproof or something..
if possible I would like to just keep it the way it is.. I have one gourami, 2 otocats and a couple snails right now.. just hopeing to get 2 zebra danios and maybe a couple frogs once this is all sorted out...
so anyone have any advice?? thanks..
and when I tested the tap water it was also after I added the de-chlorinizer but it was still 6.5.

 

if you are going for a ph of 7.0 i would give Seachem neutral regulator. it either raises or lowers ph to 7.0. i got a 8.8 oz (500-1000 gal) bottle for $11.